docs(tmdb): replace catalog titles in matching examples with stand-ins (#1658)

* docs(tmdb): replace catalog titles in matching examples with stand-ins

The Cyrillic and Arabic examples that document title folding were taken
straight from a user's own portal catalog while the folding bugs were being
diagnosed, and they spread from there into comments, fixtures, assertions and
the architecture doc. A public repository is not the place for someone's
viewing inventory, and the TMDB ids pinned alongside them identify the exact
shows.

Swap in stand-ins that reproduce the property under test rather than the
title: a word whose "й" folds away, one whose "ё" does, a two-word title
carrying a season marker, an Arabic phrase whose initial hamza decomposes into
a separate word. Every replacement was run through the real `normalizeTitle`
and `cleanTitleForSearch` before being written, so the folded keys, the wire
queries and the cache lookup keys are the same shape as before — "Лейка" and
"Леика" still meet on one key while staying two different searches, and
"AR| أمثلة تجريبية" still keys as a hamza split into a space. Real TMDB ids
become synthetic ones. One channel fixture that read as a film title becomes a
plain channel name.

Deliberately left alone: the leading-tag rule's "Akira | 1988" / "Момо | Momo"
examples in `title-normalization.util.ts`. Those are not an inventory — they
are the evidence for a regex decision measured over 1.27M catalog titles, and
inventing replacements would document a measurement that never happened.

No release note: comments, fixtures and docs only, with no behaviour change.

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

* docs(tmdb): label the folding stand-ins as illustrative, not as history

Review caught that the substitution left synthetic titles inside sentences
that assert observed fact: the architecture doc claimed a particular folded
query "returns zero results while `Лейка` returns the show" and named the
stand-ins as the titles that were searched, missed and negatively cached, and
several comments read the same way. The titles never existed, so the reading
is wrong in the one direction that matters — a future reader debugging a
regression would take them for production evidence.

Keep the claim that is actually established, which is a class-level one:
under the old single-form design every Cyrillic title carrying "й"/"ё" and
every Arabic title carrying a hamza form was searched folded, missed, and
cached as missing for the negative TTL. Present the strings themselves as
illustrative stand-ins chosen to fold the same way. The verified invariant —
what NFD does to those letters, and what the two tiers therefore produce — is
unchanged and still assertable, because it is a property of the text rather
than of any title.

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

* 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>

* docs(search): finish the fold fixtures by rewriting both halves of the pair

The last two occurrences lived in the Unicode fold corpus, which an earlier
attempt left alone after a textual substitution failed the spec. The reason it
failed is the point: one row is a precomposed/decomposed PAIR — U+0401 against
U+0415 U+0308 — asserting that both spellings fold to one string. Replacing
the visible text rewrites only the composed half and silently turns the pair
into two different words, which is not a thing a reader or a regex can see.

Rewrite both halves by code point instead, keeping the decomposed half
decomposed: U+0415 U+0308 + the new stem. Verified by decoding every quoted
string in the file afterwards, and the spec passes (534/534).

A repository-wide sweep now finds no occurrence of the replaced titles in
either normalization form.

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

---------

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

docs/architecture/tmdb-metadata-enrichment.md

@@ -537,8 +537,9 @@ identity is the query with only its case removed (`searchQueryIdentity`):
 variants are deduplicated by it and every attempted variant is cached under
 its own key (`title:<identity>|year:<y>|v4`, in the language that variant
 was searched in), never by the folded key and never only under the first
-variant — "Феик" and "Фейк" fold to one key but are different searches with
-different answers, so a verdict for one must not be read back for the other;
+variant — "Леика" and "Лейка", an illustrative pair, fold to one key while
+staying two different searches that can get different answers, so a verdict
+for one must not be read back for the other;
 a misspelled original title must not swallow the display title that TMDB
 actually knows; and two items that share an original title but not a display
 title walk different variant lists, so a row keyed on the first variant alone
@@ -547,11 +548,13 @@ splits Cyrillic "й" into "и" + a combining breve and "ё" into "е" + a
 diaeresis, and Arabic hamza forms ("أ") into a bare alef + a combining hamza
 that the punctuation step then turns into a space inside the word. The key
 drops or splits on those marks, and TMDB's `/search` does not fold them the
-same way — a query of `феик` returns zero results while `Фейк` returns the
-show. Under the old single-form design every Russian title with "й"/"ё"
-("Фейк (10 серий)", "Волшебный участок", "Молодой Шерлок") was searched
-folded, missed, and cached as missing for the 7-day negative TTL. Compare
-results only through `normalized`; never send it over the wire.
+same way, so a folded query matches nothing there. Under the old single-form
+design that hit every Russian title carrying "й" or "ё" and every Arabic
+title carrying a hamza form: each was searched folded, missed, and cached as
+missing for the 7-day negative TTL. The Cyrillic and Arabic strings used
+throughout this section are illustrative stand-ins chosen to fold the same
+way, not the titles the failures were observed on. Compare results only
+through `normalized`; never send it over the wire.
 
 Electron IPC path (follows the standard DB worker contract, see
 [SQLite DB Worker](./sqlite-db-worker.md)):