Feature: Subtitle intelligence — AI generation, auto-translate, auto-sync

[PetalCat]

Summary

Integrate Bazarr's subtitle management capabilities directly into the Nexus player and media detail pages.

Current Status

Implemented:

• Bazarr adapter setItemStatus for download, sync, translate, delete actions
• API routes: POST /api/subtitles/download, POST /api/subtitles/sync, POST /api/subtitles/translate, DELETE /api/subtitles
• Admin provider status endpoint: GET /api/admin/subtitles/providers
• Bazarr uploadContent method on adapter

Remaining gaps (from codex research):

• Translate route documents targetLanguage but doesn't forward it to Bazarr
• Bazarr Whisper translation is English-only — route should reflect this limitation
• No user-facing upload route or UI despite adapter support
• No player UI integration (buttons in subtitle picker for download/sync/translate)
• No subtitle availability badges on media detail pages

Acceptance Criteria

• Translate semantics verified against Bazarr API
• Upload route + UI flow exists end-to-end
• Player subtitle picker has action buttons
• Media detail shows subtitle status badges

[PetalCat]

Implemented — Bazarr adapter setItemStatus + uploadContent methods, subtitle download/sync/translate/delete API routes, admin provider status endpoint.

[PetalCat]

Reopening — codex research identified gaps: translate route doesn't forward targetLanguage, upload has no user-facing route/UI, Whisper translation is English-only. These need fixing before closing.