fix(core,meta,app,android,cli): number episodes the way releases do

AniList's per-season lookup searched for "<title> 2nd Season" and the
scorer picked the base entry again, so Attack on Titan seasons 2-4 and
Jigokuraku season 2 were captioned with season one's names. Episode
names came from streamingEpisodes, which is partial and numbered however
a streaming site counted. Bleach S17 and Mushishi S02/S03 had none.

AniList now walks SEQUEL relations from the match and takes each
entry's episodes from ani.zip, which carries TVDB's season, number and
absolute number. An episode row keeps all three plus its place in the
AniList entry. EpisodeGuide::get matches whichever numbering a file
uses and never answers from another season.

Episodes and fanart are stored as one enrichment. The episode list is
replaced even when empty, and the enrichment is recorded as asked, so a
film is not re-asked every run. Storing a different match drops the old
entry's episode rows. AniList's 4.75:1 bannerImage is no longer stored
as the 16:9 backdrop; ani.zip's 1920x1080 fanart is used instead.

Schema v9 adds the columns and deletes the AniList episode rows and
banners. Matches are kept. Desktop, Android and the CLI now share
service::plan and MetadataService::work. The settings text names
ani.zip. Audit and roadmap in docs/METADATA.md; bug entry B61.

crates/pstr-core/src/metadata.rs

@@ -20,7 +20,7 @@
 //! thumbnails at upload time and that client attaches none. See
 //! `docs/DEVELOPMENT.md`.
 
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 
 use serde::{Deserialize, Serialize};
 
@@ -62,7 +62,10 @@ impl ProviderId {
     /// One line on what it covers and what it costs to use.
     pub fn description(self) -> &'static str {
         match self {
-            Self::AniList => "Anime, with no API key and no account.",
+            Self::AniList => {
+                "Anime, with no API key and no account. Episode names and wide art come from \
+                 ani.zip, which is sent the matched ids."
+            }
             Self::Tmdb => "Film and television. Needs a free API key from themoviedb.org.",
         }
     }
@@ -139,6 +142,23 @@ pub struct EpisodeMetadata {
     /// anime releases name their files.
     pub season: Option<u32>,
     pub number: u32,
+    /// Its place counting straight through every season, when the provider
+    /// knows it. What an absolutely-numbered file inside a season folder —
+    /// `Attack on Titan/Season 2/… - 26.mkv` — is matched on.
+    #[serde(default)]
+    pub absolute: Option<u32>,
+    /// Its season and number counting each provider *entry* as a season: the
+    /// position of the entry it belongs to among the franchise's series
+    /// entries, and its number within that entry.
+    ///
+    /// Not TVDB's season. A release that follows AniList rather than TVDB
+    /// names Mushishi's *Zoku Shou 2* `S03`, where TVDB files it as the second
+    /// half of season two; this is what that file is answered from. See
+    /// [`EpisodeGuide::get`] for when it is allowed to be.
+    #[serde(default)]
+    pub entry_season: Option<u32>,
+    #[serde(default)]
+    pub entry_number: Option<u32>,
     pub name: Option<String>,
     pub overview: Option<String>,
     /// A frame from the episode, around 16:9.
@@ -149,6 +169,20 @@ pub struct EpisodeMetadata {
     pub air_date: Option<String>,
 }
 
+/// What enriching a matched title found: its episodes, and art the search
+/// answer did not carry.
+///
+/// Stored as one unit by `Catalog::set_enrichment`, and recorded as asked even
+/// when both are empty — a film has no episode list, and without the record it
+/// would be asked again on every match run.
+#[derive(Debug, Clone, Default, PartialEq)]
+pub struct Enrichment {
+    pub episodes: Vec<EpisodeMetadata>,
+    /// A 16:9 picture of the whole title, when one was found. `None` leaves
+    /// whatever backdrop the match already had.
+    pub backdrop_url: Option<String>,
+}
+
 /// Every episode a provider listed for one title, ready to look up.
 ///
 /// The lookup is the whole reason this is a type rather than a `Vec`: a file
@@ -160,16 +194,33 @@ pub struct EpisodeGuide {
     /// Keyed `(season, number)`, where `None` is the provider's own absolute
     /// numbering.
     entries: HashMap<(Option<u32>, u32), EpisodeMetadata>,
+    /// [`EpisodeMetadata::absolute`] to the key of the entry holding it.
+    absolute: HashMap<u32, (Option<u32>, u32)>,
+    /// [`EpisodeMetadata::entry_season`] and `entry_number` to the key of the
+    /// entry holding them.
+    by_entry: HashMap<(u32, u32), (Option<u32>, u32)>,
+    /// Every season some entry is filed under, for deciding when the entry
+    /// numbering may answer.
+    stated: HashSet<u32>,
 }
 
 impl EpisodeGuide {
     pub fn new(episodes: Vec<EpisodeMetadata>) -> Self {
-        Self {
-            entries: episodes
-                .into_iter()
-                .map(|episode| ((episode.season, episode.number), episode))
-                .collect(),
+        let mut guide = Self::default();
+        for episode in episodes {
+            let key = (episode.season, episode.number);
+            if let Some(absolute) = episode.absolute {
+                guide.absolute.insert(absolute, key);
+            }
+            if let (Some(season), Some(number)) = (episode.entry_season, episode.entry_number) {
+                guide.by_entry.insert((season, number), key);
+            }
+            if let Some(season) = episode.season {
+                guide.stated.insert(season);
+            }
+            guide.entries.insert(key, episode);
         }
+        guide
     }
 
     pub fn is_empty(&self) -> bool {
@@ -182,20 +233,25 @@ impl EpisodeGuide {
 
     /// What the provider says about the file numbered like this.
     ///
-    /// Tried in order: the season and number the filename states; the
-    /// provider's absolute numbering; and, for a file with no season at all,
-    /// season one. That second fallback is what makes an absolutely-numbered
-    /// release line up with a provider that files everything under a single
-    /// season — the common case for anime on TMDB.
+    /// Tried in order:
     ///
-    /// **The absolute fallback stops at season one.** A provider that numbers
-    /// straight through is one that split nothing, so its episode seven is the
-    /// seventh of the show — which is season one's, not season two's. Answering
-    /// `S02E07` with it captions every episode of every later season with the
-    /// wrong name, and a wrong caption does not look like a bug: it looks like
-    /// the library is wrong. Season two upwards is answered from an entry that
-    /// states that season or not at all — see
-    /// `Provider::seasons_are_separate_entries`.
+    /// 1. the season and number the filename states;
+    /// 2. for a file in no season or in season one, the provider's own absolute
+    ///    list, and for a file in no season, season one — what makes `#057`
+    ///    line up with TMDB filing a 64-episode anime under one season;
+    /// 3. the absolute number, into the season the file states — what makes
+    ///    `Season 2/… - 26.mkv` the second season's first episode;
+    /// 4. the entry numbering, for a season the provider files nothing under.
+    ///
+    /// **No fallback crosses into another season.** Step 2 stops at season one
+    /// and step 3 only answers inside the season the file named, because
+    /// answering `S02E07` with season one's seventh episode captions every
+    /// episode of every later season with the wrong name — and a wrong caption
+    /// does not look like a bug, it looks like the library is wrong. Step 4
+    /// only answers a season the provider has nothing filed under, so a release
+    /// numbered the provider's way is never re-read the other way: Mushoku
+    /// Tensei's second *entry* is the second half of season one, and its
+    /// `S02E01` is season two's.
     pub fn get(&self, season: Option<u32>, number: u32) -> Option<&EpisodeMetadata> {
         if let Some(found) = self.entries.get(&(season, number)) {
             return Some(found);
@@ -205,14 +261,31 @@ impl EpisodeGuide {
         {
             return Some(found);
         }
-        season
-            .is_none()
-            .then(|| self.entries.get(&(Some(1), number)))?
+        if season.is_none()
+            && let Some(found) = self.entries.get(&(Some(1), number))
+        {
+            return Some(found);
+        }
+        if let Some(found) = self
+            .absolute
+            .get(&number)
+            .and_then(|key| self.entries.get(key))
+            && (season.is_none() || found.season == season)
+        {
+            return Some(found);
+        }
+        let season = season?;
+        if self.stated.contains(&season) {
+            return None;
+        }
+        self.by_entry
+            .get(&(season, number))
+            .and_then(|key| self.entries.get(key))
     }
 
     /// Which seasons this guide actually has answers for. `None` is the
     /// provider's own absolute numbering.
-    pub fn seasons(&self) -> std::collections::HashSet<Option<u32>> {
+    pub fn seasons(&self) -> HashSet<Option<u32>> {
         self.entries
             .values()
             .map(|episode| episode.season)
@@ -335,6 +408,9 @@ mod tests {
         EpisodeMetadata {
             season,
             number,
+            absolute: None,
+            entry_season: None,
+            entry_number: None,
             name: Some(name.into()),
             overview: None,
             still_url: None,
@@ -342,6 +418,89 @@ mod tests {
         }
     }
 
+    /// An episode as ani.zip describes one: TVDB's season and number, TVDB's
+    /// absolute number, and its place in the AniList entry it came from.
+    fn numbered(
+        (season, number): (u32, u32),
+        absolute: u32,
+        (entry_season, entry_number): (u32, u32),
+        name: &str,
+    ) -> EpisodeMetadata {
+        EpisodeMetadata {
+            absolute: Some(absolute),
+            entry_season: Some(entry_season),
+            entry_number: Some(entry_number),
+            ..episode(Some(season), number, name)
+        }
+    }
+
+    fn name_of(guide: &EpisodeGuide, season: Option<u32>, number: u32) -> Option<String> {
+        guide.get(season, number).and_then(|e| e.name.clone())
+    }
+
+    /// `Attack on Titan/Season 2/[Anime Time] Attack On Titan - 26.mkv`: a
+    /// season folder full of absolutely-numbered files.
+    #[test]
+    fn an_absolute_number_in_a_season_folder_finds_that_seasons_episode() {
+        let guide = EpisodeGuide::new(vec![
+            numbered((1, 1), 1, (1, 1), "To You, in 2000 Years"),
+            numbered((2, 1), 26, (2, 1), "Beast Titan"),
+        ]);
+        assert_eq!(name_of(&guide, Some(2), 26).as_deref(), Some("Beast Titan"));
+        // And with no season at all, the absolute number is the whole answer.
+        assert_eq!(name_of(&guide, None, 26).as_deref(), Some("Beast Titan"));
+    }
+
+    /// The absolute fallback must not carry a file into a season it did not
+    /// name: `S03E13` of a show whose 13th episode is in season one is not that
+    /// episode.
+    #[test]
+    fn an_absolute_number_never_answers_for_another_season() {
+        let guide = EpisodeGuide::new(vec![
+            numbered((1, 13), 13, (1, 13), "Season one's thirteenth"),
+            numbered((3, 1), 38, (3, 1), "Smoke Signal"),
+        ]);
+        assert_eq!(guide.get(Some(3), 13), None);
+    }
+
+    /// Mushishi: TVDB files both halves of *Zoku Shou* as season two, and the
+    /// release calls the second half `S03`. Season three exists nowhere at the
+    /// provider, so the entry numbering answers it.
+    #[test]
+    fn a_season_the_provider_does_not_have_is_answered_by_entry() {
+        let guide = EpisodeGuide::new(vec![
+            numbered((1, 1), 1, (1, 1), "The Green Seat"),
+            numbered((2, 1), 28, (2, 1), "The Hand That Caresses the Night"),
+            numbered((2, 11), 39, (3, 1), "Lightning's End"),
+        ]);
+        assert_eq!(
+            name_of(&guide, Some(3), 1).as_deref(),
+            Some("Lightning's End")
+        );
+        assert_eq!(
+            name_of(&guide, Some(2), 1).as_deref(),
+            Some("The Hand That Caresses the Night")
+        );
+    }
+
+    /// Mushoku Tensei: AniList's second entry is the second half of TVDB's
+    /// season one. A release numbered TVDB's way names season two `S02`, and
+    /// the entry numbering must not answer it with that second half.
+    #[test]
+    fn the_entry_numbering_never_overrides_a_season_the_provider_has() {
+        let guide = EpisodeGuide::new(vec![
+            numbered((1, 12), 12, (2, 1), "Cour two's first"),
+            numbered((2, 1), 26, (3, 1), "Season two's first"),
+        ]);
+        assert_eq!(
+            name_of(&guide, Some(2), 1).as_deref(),
+            Some("Season two's first")
+        );
+        // A second-season episode the provider does not list is unanswered,
+        // not answered from the entry numbering.
+        assert_eq!(guide.get(Some(2), 2), None);
+    }
+
     #[test]
     fn a_file_that_states_its_season_is_answered_from_that_season() {
         let guide = EpisodeGuide::new(vec![