Allows users to configure the max_tokens sent to the AI endpoint for
each activity (tagging, description, extraction, translation) individually,
with per-library overrides following the same pattern as model overrides.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
- Add library_ai_settings table with migration for per-library overrides
- Extend AiConfig with editable prompt parts for description, tagging,
extraction, and translation steps; defaults match previous hardcoded values
- Add getEffectiveAiConfig(libraryId) that merges global settings with
library-level overrides (empty override falls through to global)
- Update all ai-tagger functions to use getEffectiveAiConfig and build
prompts from configurable parts
- Add GET/PUT /api/ai-settings/library/[id] for per-library overrides
- Update /api/ai-settings GET/PUT to include prompt fields
- Add Prompts section and Library Overrides section to admin UI
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
