docs(04-01): complete tag schema and repository plan

Tasks completed: 2/2
- Add tags schema with case-insensitive unique index
- Create tagRepository with tag operations

SUMMARY: .planning/phases/04-tags/04-01-SUMMARY.md

.planning/STATE.md

@@ -19,9 +19,9 @@ Progress: [████████░░] 85%
 ## Performance Metrics
 
 **Velocity:**
-- Total plans completed: 11
+- Total plans completed: 12
 - Average duration: 3.6 min
-- Total execution time: 44 min
+- Total execution time: 46 min
 
 **By Phase:**
 
@@ -30,10 +30,10 @@ Progress: [████████░░] 85%
 | 01-foundation | 2 | 7 min | 3.5 min |
 | 02-core-crud | 4 | 15 min | 3.75 min |
 | 03-images | 4 | 14 min | 3.5 min |
-| 04-tags | 1 | 8 min | 8 min |
+| 04-tags | 2 | 10 min | 5 min |
 
 **Recent Trend:**
-- Last 5 plans: 03-01 (4 min), 03-02 (2 min), 03-03 (2 min), 03-04 (8 min), 04-02 (8 min)
+- Last 5 plans: 03-02 (2 min), 03-03 (2 min), 03-04 (8 min), 04-02 (8 min), 04-01 (2 min)
 - Trend: Stable
 
 *Updated after each plan completion*
@@ -74,6 +74,9 @@ Recent decisions affecting current work:
 - Fetch/invalidateAll pattern for pin toggle actions (04-02)
 - Due date stored as ISO string from HTML5 date input (04-02)
 - Pinned section uses uppercase label for visual distinction (04-02)
+- Tags stored with original case but matched case-insensitively (04-01)
+- Entry tags replaced atomically via delete-then-insert (04-01)
+- lower() helper for case-insensitive SQL queries (04-01)
 
 ### Pending Todos
 
@@ -86,9 +89,9 @@ None yet.
 ## Session Continuity
 
 Last session: 2026-01-31
-Stopped at: Completed 04-02-PLAN.md
+Stopped at: Completed 04-01-PLAN.md (2/3 plans complete in phase 4)
 Resume file: None
 
 ---
 *State initialized: 2026-01-29*
-*Last updated: 2026-01-31 after 04-02 completion*
+*Last updated: 2026-01-31 after 04-01 completion*