docs(21-01): complete detail pages plan — item detail with edit mode, catalog Add button

- SUMMARY.md with task commits and known stubs
- STATE.md updated to phase 21, plan 1 of 3 complete
- ROADMAP.md updated with plan progress

.planning/STATE.md

@@ -3,7 +3,7 @@ gsd_state_version: 1.0
 milestone: v1.3
 milestone_name: Research & Decision Tools
 status: planning
-stopped_at: Completed 20-02-PLAN.md
+stopped_at: Completed 21-01-PLAN.md
 last_updated: "2026-04-06T06:17:39.050Z"
 last_activity: 2026-04-06
 progress:
@@ -25,9 +25,9 @@ See: .planning/PROJECT.md (updated 2026-04-03)
 
 ## Current Position
 
-Phase: 20 of 18 (PostgreSQL Migration)
-Plan: Not started
-Status: Ready to plan
+Phase: 21 of 21 (Item & Catalog Detail Pages)
+Plan: 1 of 3 complete
+Status: Executing
 Last activity: 2026-04-06
 
 Progress: [----------] 0% (v2.0 milestone)
@@ -58,6 +58,8 @@ Key decisions made during v2.0 planning:
 - [Phase 20]: Created tags table in schema (was missing, needed for GET /api/tags endpoint)
 - [Phase 20]: FAB visible on all authenticated routes, not just collection gear tab
 - [Phase 20]: Add button on catalog search cards is a stub (Phase 21 wires actual flow)
+- [Phase 21]: Edit mode on detail pages uses local useState, not UIStore panel state
+- [Phase 21]: Add to Collection button on catalog detail page is a stub (Phase 22 wires actual flow)
 
 ### Pending Todos
 
@@ -76,6 +78,6 @@ None active.
 
 ## Session Continuity
 
-Last session: 2026-04-06T06:12:00.000Z
-Stopped at: Completed 20-02-PLAN.md
+Last session: 2026-04-06T13:02:00.000Z
+Stopped at: Completed 21-01-PLAN.md
 Resume file: None