feat(storage): add migration v2 — task fields, FTS5 search, timer state
- Migration v2: adds priority, project, status, updated_at, sort_order, notes columns to tasks table
- FTS5 virtual table on transcripts with insert/update/delete triggers for automatic index sync
- Timer state table for persisting active countdown timers across app restarts
- New database functions: insert_task_v2, update_task_v2, reorder_tasks, list_tasks_by_status, search_transcripts, save/get/clear_timer_state
- TimerStateRow type for timer persistence
- Extended TaskRow with v2 fields
- Fixed migration runner to handle BEGIN...END blocks in CREATE TRIGGER statements
- All 11 tests passing, Tauri app compiles cleanly
d79ad40b33