docs(03-02): complete collapsible sections integration plan

- 03-02-SUMMARY.md: documents CollapsibleSections wired into dashboard
- STATE.md: records key-prop reset decision, phase 3 completion, updated session
- ROADMAP.md: phase 3 plans (2/2) marked complete

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.planning/STATE.md

@@ -3,14 +3,14 @@ gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
 status: planning
-stopped_at: Completed 03-01-PLAN.md — CategorySection, CollapsibleSections, carryover display built
-last_updated: "2026-03-17T14:09:55.087Z"
+stopped_at: Completed 03-02-PLAN.md — CollapsibleSections wired into dashboard, Phase 3 complete
+last_updated: "2026-03-17T14:15:02.065Z"
 last_activity: 2026-03-16 — Phase 2 complete, transitioned to Phase 3
 progress:
   total_phases: 4
-  completed_phases: 2
+  completed_phases: 3
   total_plans: 7
-  completed_plans: 6
+  completed_plans: 7
   percent: 100
 ---
 
@@ -56,6 +56,7 @@ Progress: [████████████████████] 5/5 pla
 | Phase 02 P01 | 2min | 2 tasks | 4 files |
 | Phase 02-dashboard-charts-and-layout P03 | 3min | 2 tasks | 2 files |
 | Phase 03-collapsible-dashboard-sections P01 | 2min | 2 tasks | 8 files |
+| Phase 03-collapsible-dashboard-sections P02 | 2min | 1 tasks | 2 files |
 
 ## Accumulated Context
 
@@ -80,6 +81,7 @@ Recent decisions affecting current work:
 - [Phase 03-collapsible-dashboard-sections]: CategorySection uses controlled open/onOpenChange pattern — Plan 02 will own open state in DashboardContent
 - [Phase 03-collapsible-dashboard-sections]: Direction-aware diff: spending types (bill, variable_expense, debt) over when actual > budgeted; income/saving/investment over when actual < budgeted
 - [Phase 03-collapsible-dashboard-sections]: CollapsibleContent wired to CSS keyframes via data-[state=open]:animate-collapsible-open Tailwind variant
+- [Phase 03-collapsible-dashboard-sections]: key prop state reset over useEffect: keying DashboardContent by budgetId causes full remount on month change, cleanly resetting openSections without violating react-hooks linter rules
 
 ### Pending Todos
 
@@ -91,6 +93,6 @@ None yet.
 
 ## Session Continuity
 
-Last session: 2026-03-17T14:09:55.085Z
-Stopped at: Completed 03-01-PLAN.md — CategorySection, CollapsibleSections, carryover display built
+Last session: 2026-03-17T14:15:02.063Z
+Stopped at: Completed 03-02-PLAN.md — CollapsibleSections wired into dashboard, Phase 3 complete
 Resume file: None