fix(matching): keep abbreviation titles out of bare-year keys (#1426)

A leading 2-5 character uppercase token before a dash, pipe or colon was
always read as a provider tag, so a film whose NAME is such a token lost it and
normalized down to its release year alone. "AKA - 2023" became the key "2023",
where it collided with BDE, BRO, OUT, WIL and IF — and they were offered to
each other as alternative sources in VOD multi-source.

"IT - 65 (2023)" (the Italian copy of the film "65") is structurally identical,
so only the token's meaning can separate them. The leading token is now tested
against a vocabulary — TRAILING_TAG_VOCABULARY plus a prefix-only list derived
from the real catalog — but only when the strip would leave no real word
behind. A compound is read by its head, so the open-ended "4K-<lang>" family
keeps working while "INU-OH" and "PC-4L" are recognized as film names. An
unknown token keeps its title: a refused strip costs one unmatched copy, a
wrong one corrupts that film's identity in VOD multi-source, the TMDB Similar
rail, DB_MATCH_TITLES and pin keys.

"No real word" is decided by running the rest of the pipeline on the stripped
form and looking at what comes out, never by re-implementing what later stages
remove. Quality tags, trailing and underscore tags, double-dash suffixes and
season markers each otherwise smuggle the strip through, and a stage added
later is covered for free.

Validated over the live catalog, movies and series: 83 keys fixed, 0 corrupted
across 1,616,111 titles. Deriving the vocabulary from movies alone missed AMZ,
D+ and P+ and broke the Paramount+/Disney+ copies of the numeric series 1923,
1883, 24 and 9-1-1.

.changes/matching-abbreviation-titles.md

@@ -0,0 +1,10 @@
+---
+type: fix
+area: matching
+---
+
+Movies whose name is a short abbreviation — AKA, RRR, IO, VFW, Y2K — are no
+longer mistaken for a language tag and filed under their release year alone.
+They now match their own copies in your other playlists, so alternative
+sources, recommendations and pinned sources land on the right film instead of
+an unrelated one that happens to share that year.