feat(meta,core,app,android,ios): AniSkip where files have no chapters

Most files that are not fansub releases carry no chapters, so they had no
skip button. AniSkip knows where an episode's opening and ending are, by
MyAnimeList id and episode number. ani.zip sends each entry's MyAnimeList
id and enrichment now keeps it on every episode row; schema v14 adds the
column and marks AniList titles un-enriched, deleting nothing, as v13 did.

When a file has loaded with no chapter naming an opening or ending, and
its length is known, each client asks once, with enrichment on only. The
answer lives as long as the file is open. with_skip_ranges cuts it into
the chapters as chapters named Opening and Ending, so the skip button,
auto-skip, the up-next countdown and the seek bar's marks all work
through the code a chaptered file uses. A file's own opening or ending
always wins over AniSkip's.

PRIVACY.md lists what is sent: the MyAnimeList id, the episode number and
the file's length.

docs/METADATA.md

@@ -45,6 +45,7 @@ good. What hung off it was not:
 |---|---|---|
 | **AniList** GraphQL | none | Identity. Search, every alias, cover art, relations (`SEQUEL`, `PREQUEL`, `SIDE_STORY`…), studios, staff, tags, format, season, popularity, next airing episode, the MAL id. |
 | **ani.zip** `api.ani.zip/mappings?anilist_id=` | none | Everything AniList lacks, per AniList id: TVDB season, episode and absolute numbers; episode titles in several languages; TVDB synopses; 16:9 stills; air dates; runtime. Series art: TVDB **fanart at 1920×1080**, poster, banner, logo. Cross-ids for MAL, AniDB, TVDB, TMDB, Kitsu, IMDb. A community service — cache what it says. |
+| **AniSkip** `api.aniskip.com/v2/skip-times/` | none | Where an episode's opening and ending are, by MyAnimeList id and episode number, as viewers marked them. Asked at play time for files without such chapters; never stored. |
 | **TMDB** | free key | Film backdrops and logos; live-action TV. Chosen as the provider, or with AniList chosen, asked by id for art alone. |
 | **TVmaze** | none | Live-action TV: episodes with 16:9 stills and runtimes, network, status, full-HD backgrounds. No films; its "typography" art is a JPEG, so no logos. In use after AniList. |
 | **AniSkip** | none | Opening and ending timestamps by MAL id and episode. |
@@ -212,6 +213,27 @@ deleting nothing. `TitleDetails::revision` makes details written before
 `runtime` existed refetch by id on the next run; they stay on screen until the
 answer lands, rather than being blanked by the migration as schema v10 did.
 
+**AniSkip.** A file whose chapters name no opening or ending — most files
+that are not fansub releases — gets them from [AniSkip](https://aniskip.com),
+where viewers mark where an episode's opening and ending are. ani.zip sends each
+entry's MyAnimeList id with its mappings; enrichment now keeps it on every
+episode row (`episode_metadata.mal_id`), next to the episode's number within
+that entry. When such a file has loaded and its length is known, the player asks
+`api.aniskip.com/v2/skip-times/{mal_id}/{number}?types=op&types=ed&episodeLength=`
+once, with enrichment on only. The answer is kept in memory for as long as the
+file is open and never stored.
+
+`pstr_core::chapters::with_skip_ranges` cuts the answer into the file's
+chapters as chapters named `Opening` and `Ending`, so the skip button, skipping
+on its own, the up-next countdown and the marks on the seek bar all work through
+the same code as for a file that came with them. A file whose own chapters
+already name an opening or an ending keeps them: what a release says about its
+own cut beats what a viewer of another release marked.
+
+**Schema v14** adds the column and marks every AniList title un-enriched,
+deleting nothing, as v13 did. Until the next match run fills it in, AniSkip is
+not asked.
+
 ## Phase 3 — reach
 
 **Routing by title (done).** One provider for the whole library left Game of

docs/MOBILE.md

@@ -33,6 +33,8 @@ your Drive**. See [Account and sync](ACCOUNT_AND_SYNC.md).
   the middle to pause.
 - The menu has **Episodes**, **Chapters**, **Playback speed**, the audio and subtitle tracks, and
   **Lock to landscape**.
+- **Skip opening** and **Skip ending** work as on the desktop, AniSkip included: see
+  [The player](USER_GUIDE.md#the-player).
 - Sound keeps playing with the screen off or the app in the background, with controls on the lock
   screen. Turn off **Background audio** in Settings to stop that.
 

docs/PRIVACY.md

@@ -11,6 +11,7 @@ and to nothing else unless you turn on posters and descriptions. This page lists
 | AniList and ani.zip, or TMDB | The names of the titles in your library, and the ids of matched titles | Only with **Posters and descriptions** on |
 | TVmaze | With AniList chosen: the names of the titles AniList has no match for, and the ids of those TVmaze matched | Only with **Posters and descriptions** on |
 | TMDB, with AniList chosen | The TMDB ids of matched titles that have no wide picture or logo yet. Never a title's name | Only with **Posters and descriptions** on and a TMDB key saved |
+| AniSkip | The MyAnimeList id and episode number of what you play, and the file's length. Never a name | Only with **Posters and descriptions** on, when you play an episode whose file does not mark its opening and ending |
 
 Nothing else leaves your device. There is no telemetry, no crash reporting and no update check.
 

docs/USER_GUIDE.md

@@ -135,7 +135,8 @@ An episode counts as watched once you have seen 90% of it.
 The picture plays inside the app's window. Move the mouse to show the controls.
 
 - **Skip opening** and **Skip ending** appear when the file's chapters mark an opening, an ending
-  or a preview. Files without chapter names get no skip button. Turn on **Skip openings and
+  or a preview. For an anime whose file marks neither, the app asks AniSkip where they are, with
+  **Posters and descriptions** on; they then show as chapters too. Turn on **Skip openings and
   credits** in Settings to skip them without asking.
 - **Up next** counts down 10 seconds when the credits start, then plays the next episode. Choose
   **Play now**, **Cancel** or **Watch till the end**.