docs(20-01): complete tags API, route registration, and UI state plan

- Add 20-01-SUMMARY.md with execution results
- Update STATE.md with progress and decisions

.planning/STATE.md

@@ -3,14 +3,14 @@ gsd_state_version: 1.0
 milestone: v1.3
 milestone_name: Research & Decision Tools
 status: planning
-stopped_at: Completed 18-05-PLAN.md
-last_updated: "2026-04-05T11:22:25.312Z"
+stopped_at: Completed 20-01-PLAN.md
+last_updated: "2026-04-06T05:59:26.689Z"
 last_activity: 2026-04-05
 progress:
-  total_phases: 12
+  total_phases: 13
   completed_phases: 11
   total_plans: 33
-  completed_plans: 31
+  completed_plans: 32
   percent: 0
 ---
 
@@ -55,6 +55,7 @@ Key decisions made during v2.0 planning:
 - Separate globalItems table — not a flag on user items table
 - Single-user SQLite mode diverges at v2.0 boundary
 - [Phase 18]: Profile data loaded via usePublicProfile(userId) not /auth/me extension
+- [Phase 20]: Created tags table in schema (was missing, needed for GET /api/tags endpoint)
 
 ### Pending Todos
 
@@ -67,6 +68,6 @@ None active.
 
 ## Session Continuity
 
-Last session: 2026-04-05T11:20:56.920Z
-Stopped at: Completed 18-05-PLAN.md
+Last session: 2026-04-06T05:59:26.687Z
+Stopped at: Completed 20-01-PLAN.md
 Resume file: None