feat: improve DeepLX translation, rich messages, and locale handling

[d9k6s]

Summary

• improve DeepLX long-message segmentation while preserving supported formatting and protected entities
• add Rich Message text extraction and translation, and expose the translation action when a rich message contains translatable text
• normalize every CharSequence to plain text at the shared translator boundary before provider dispatch and cache lookup, including SpannableStringBuilder inputs from bot information cards
• keep cancellation semantics intact and route provider/input failures through the existing translation error callback instead of crashing the main thread
• isolate automatic translation settings per dialog and topic, migrate legacy positive chat keys, and resolve effective settings in the order topic override -> parent dialog -> global default
• complete Traditional Chinese resources and map official Hant/Hans language packs to the correct Android resource locale
• add lightweight regression coverage for locale resolution, dialog/topic inheritance, legacy-key migration, and Rich Message extraction

Follow-up update

This branch now includes the latest upstream/main (b5c427cecccb2391f3054cc8d5bceb6bafc01059) and the fixes developed after the original draft was opened:

• support non-String CharSequence translation inputs without Unsupported translation query crashes
• make topics without an explicit override inherit the parent group setting before falling back to the global setting
• keep an explicit topic enable/disable value at the highest priority

Validation

• :TMessagesProj:compileDebugJavaWithJavac — BUILD SUCCESSFUL with Java 17 / Gradle 9
• LanguageResourceLocaleTest — passed
• AutoTranslateConfigKeyTest — passed
• RichMessageTextProcessorTest — passed
• modified locale XML files parsed successfully
• conflict-marker scan and git diff --check — clean
• all four PR commits have valid GPG signatures

Scope note

The PR remains limited to 22 application source, resource, and regression-test files. Fork-only automation, including .github/workflows/test-apk.yml and .github/scripts/sync-dev-to-main.ps1, is intentionally excluded.