docs(tmdb): finish the sweep — a missed cache key and a last observed-fact claim

Two spots the first pass left behind:

- `tmdb-search-cache-cleanup.spec.ts` kept a catalog-derived lookup key
  verbatim. Only the TMDB id beside it had been swapped, because the sweep
  matched the title in its display casing and the key stores it lowercased —
  so one item of the inventory stayed in the repository, twice.
- `SearchTitleVariant`'s doc comment still asserted that one specific folded
  string finds nothing on TMDB. State the mechanism instead: folding rewrites
  the letters the search matches on, so the folded form finds nothing there.

`content-search.util.sqlite.spec.ts` gets a channel fixture that no longer
reads as a film title.

`search-text-fold.util.spec.ts` is deliberately left alone. Its "Ёлки" is a
common noun sitting in a Unicode corpus beside "Amélie", "İnşaat" and "Ά",
not an inventory entry — and its rows are precomposed/decomposed PAIRS
(U+0401 against U+0415 U+0308). A textual substitution rewrites only the
composed half and silently turns the pair into two different words; doing it
failed that spec, which is what a fixture encoding an invisible property is
for.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

libs/shared/database/src/lib/tmdb-search-cache-cleanup.spec.ts

@@ -63,7 +63,7 @@ it('drops only retired search rows across skipped, previous, pre-person, fresh a
         hooks.runMigrations(skipped);
         const skippedAfter = snapshot(skipped);
         // Next startup: a row written meanwhile under the current key survives
-        skipped.prepare("INSERT INTO tmdb_metadata (media_type, lookup_key, language, tmdb_id) VALUES ('tv', 'title:гудовы|year:2026|v4', 'ru-RU', 101103)").run();
+        skipped.prepare("INSERT INTO tmdb_metadata (media_type, lookup_key, language, tmdb_id) VALUES ('tv', 'title:сосенка|year:2026|v4', 'ru-RU', 101103)").run();
         hooks.runMigrations(skipped);
         const repeated = snapshot(skipped);
         // Previous release: the earlier cleanups already ran; only v3 rows go
@@ -124,7 +124,7 @@ it('drops only retired search rows across skipped, previous, pre-person, fresh a
             markers: [V2_MARKER, V3_MARKER, V4_MARKER],
         },
         repeated: {
-            keys: [...survivors, 'title:гудовы|year:2026|v4'].sort(),
+            keys: [...survivors, 'title:сосенка|year:2026|v4'].sort(),
             payloads: detailsPayloads,
             markers: [V2_MARKER, V3_MARKER, V4_MARKER],
         },