Add support for Carousel-style dashboard with unified collections architecture:
Database Schema Changes:
- Add user_dashboard_preferences table:
- hidden_collections: TEXT[] for managing section visibility
- collection_order: TEXT[] for custom ordering
- items_per_section: INT for limiting items per section
- Update collections table:
- user_id: Make nullable to support system-owned collections (NULL = system)
- show_on_dashboard: BOOLEAN for controlling visibility
- query_type: TEXT for different query types (continue-reading, recently-added, etc.)
- priority: INT for display order (lower = higher priority)
- is_system_collection: BOOLEAN for flagging system defaults
- Update collection_items table:
- Add excluded BOOLEAN for user overrides of auto-assigned items
Indexes:
- idx_collections_dashboard: (user_id, show_on_dashboard, priority) WHERE show_on_dashboard = true
- idx_dashboard_prefs_user_library: (user_id, library_id)
- idx_collection_items_excluded: (collection_id, excluded) WHERE excluded = true
System Collections (pre-seeded defaults):
- continue-reading: Books with 0 < progress < 1
- recently-added: Newly added items to library
- recently-read: Books with progress >= 1
- not-started: Books with progress = 0 or no record
This implements Phase 1 of the Carousel-style dashboard redesign plan.