feat(core,meta,app,android,ios,cli): TVmaze for the shows AniList does not have

With AniList chosen, a title AniList has no match for is now searched on
TVmaze, keyless, before it is given up on. One provider for the whole library
left live-action shows in a share of anime unmatched, and switching to TMDB
would have dropped every AniList match, chain and shelf.

The service holds a chain of providers. A match is stored under the provider
that gave it, and enrichment and refreshes go to that provider; a miss is
stored under the last provider asked, and is_fresh only trusts a miss from the
end of the chain, so AniList misses stored before this are asked again at once.
A provider failure still ends the lookup instead of falling through.

The hand matcher searches every provider in the chain and labels each result
with its source. TVmaze is never offered in the settings and is not asked
about titles known to be films.

docs/METADATA.md

@@ -46,7 +46,7 @@ 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. |
 | **TMDB** | free key | Film backdrops and logos; live-action TV. Already implemented. |
-| **TVmaze** | none | Live-action TV episodes, keyless. |
+| **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. |
 | **Jikan** (MAL) | none | Filler and recap flags. Timed out when tried; optional. |
 | **manami-project/anime-offline-database** | none | Every anime with its synonyms, ids and relations, as one 6 MB `.zst`. Matching against it locally sends no title anywhere. |
@@ -192,9 +192,37 @@ answer lands, rather than being blanked by the migration as schema v10 did.
 
 ## Phase 3 — reach
 
+**Routing by title (done).** One provider for the whole library left Game of
+Thrones unmatched in a share of anime, and switching the library to TMDB would
+have thrown away every AniList match, chain and shelf. So the providers are now
+asked in a chain (`pstr_meta::service::chain_of`): with AniList chosen, a title
+AniList has no match for is searched on TVmaze, keyless, before it is given up
+on. TMDB, which has television itself, is still asked alone.
+
+- A match is stored under the provider that gave it, and everything after it
+  — enrichment, refreshing details by id — goes to that provider.
+- A miss is stored under the *last* provider asked. `MetadataRecord::is_fresh`
+  takes the chain, and a miss only stands when the chain ends with the provider
+  that stored it. So an AniList miss from before TVmaze joined is not trusted,
+  and the next run asks TVmaze at once rather than after the miss expires.
+- A provider that fails (a timeout, a 429) ends the lookup with an error rather
+  than falling through. The next provider's answer for a title AniList could
+  not be asked about is a guess about an anime, and a guess stored as a match
+  would stay.
+- TVmaze is not asked about a title the library knows to be a film. It has
+  none, and a show sharing a film's name is far more often wrong than an
+  adaptation.
+- A hand search asks every provider in the chain and labels each result with
+  the provider it came from; picking one pins the title to that provider.
+
+TVmaze answers search with whole show records — genres, network, status,
+premiere date, runtime, rating — so a match carries its details with no second
+request. Enrichment is one more: `/shows/{id}` with the episodes and images
+embedded. Specials, which TVmaze numbers nowhere a file would, are left out.
+
+Still to do:
+
 - **Local matching** against the offline database, so only ids leave the
   machine.
-- **Routing by title**: AniList first, then TMDB (with a key) or TVmaze for
-  whatever is not anime — Game of Thrones in a mostly-anime share.
 - **Skip intro** from AniSkip for files without chapters, and filler flags from
   Jikan.