The review UI's language dropdown did nothing: every selection kept
rendering the English text. Two independent causes, both fixed.
1. The translations were never being read. The pipeline's
`utterance_translations` table holds one row in Deal Hunter, and that
row stores the *English* text under a `zh-Hans` code. The real
translations live in the on-disk sample files under
`samples/translations/`. `umbraaudio/translations.py` now resolves both
sources and merges them by (chapter_id, utterance_index): the table wins
where it holds a real translation, the sample files fill the gaps. A
candidate whose text is identical to the source is a placeholder, not a
translation, so it is ignored - otherwise the page would show English
under a Chinese heading and claim it was translated.
2. The query that read them was broken. `language_routes.py` selected
`u.index` and `u.speaker`; the columns are `utterance_index` and
`speaker_name`, so every read raised `sqlite3.OperationalError: near
"index": syntax error` and `/language-mockup` returned 500. It also
opened `<project>/project.db` - a 0-byte decoy - instead of
`<project>/.umbra/project.db`, the file that actually holds the data.
Also in this commit:
* The chapter review page honours `?lang=`, remembers the choice in a
cookie (set by a middleware, so it survives on every page), and shows the
selected language's *name* in the "has not been translated yet" message.
* The page now shows the translation, not the source, and the edit box is
bound to the source text so saving cannot overwrite the English with the
Chinese.
* The stray language selector that sat after `</html>` in base.html is
gone; the chapters-list page's dropdown had zero options because the
route never passed the language list.
* The language tag is wired into generation: `utterance.language_code`
(NULL = project source language) reaches `engine.generate()` and the
staleness marker, so a retagged line is re-rendered instead of keeping
English phonology behind an unchanged text. The marker records the
language; a marker written before the tag existed means English, so the
~4,300 existing clips are not invalidated.
* `project.source_language` (spec 31 section 13.1) records the book's own
language, with a migration for existing project DBs.
* A scene-break marker deliberately records no language: it is silence,
identical in every language, and tagging it would claim a phonology the
audio does not have.
Tests: 883 passed / 8 failed - the same 8 pre-existing failures
(2 test_pronunciation, 6 voice_profile_manager accent). 26 new tests
cover the resolver and the generation wiring. ruff introduces no new
findings.
2b294d7fa4