Complete the Language enum unification (commit 0dc491e) for the PyQt
GUI, which was left resolving languages from kokoro letter codes
(voice[0]) while domain and WebUI already used Language enums.
- selected_lang is now always a Language enum: voices resolve via
language_for_voice_id(), profiles via resolve_profile_language()
- kokoro letter->Language mapping stays in the engine (new public
language_for_code()); the Language.from_code() domain shim is removed
- legacy profile files with letter codes ("a", "e", ...) are tolerated
only at the profile read boundary; new profiles save ISO codes
- conversion.py letter comparisons replaced with enum comparisons, and
SynthParams lang_code= -> language= (would TypeError at runtime)
- subtitle dropdown enabled for all languages; word-count and
highlighting modes restricted to English with auto-switch to Sentence
- tests: engine mapping + profile language resolution added; 1566 pass
Deniz Şafak
11274ad6bf