normalize_tag_name now only capitalizes the first letter of each word and
leaves the rest of the word untouched (was lowercasing the tail, which turned
DC→Dc / NSFW→Nsfw). This matches ml/tag_name._title_word, so a Camie-suggested
tag keeps the exact casing the suggestion UI showed when it round-trips through
POST /api/tags on Accept — addressing "auto-suggested tags must obey
capitalization" and "don't mangle acronyms" in one rule.
Trade-off (operator-chosen): all-caps input no longer folds to Title Case, so
case-variant merging in #714 still folds the dominant lowercase-vs-Title case
but leaves all-caps stylizations distinct (protecting acronyms wins). Tests
updated + a new test documenting acronym preservation / non-folding.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>