docs(04-03): complete Export/Import/Reset plan

- SUMMARY.md with plan results and decisions
- STATE.md updated with progress and metrics
- ROADMAP.md and REQUIREMENTS.md updated

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.planning/STATE.md

@@ -3,8 +3,8 @@ gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
 status: executing
-stopped_at: Completed 04-02-PLAN.md
-last_updated: "2026-03-29T16:17:26.933Z"
+stopped_at: Completed 04-03-PLAN.md
+last_updated: "2026-03-29T16:17:42.908Z"
 last_activity: 2026-03-29
 progress:
   total_phases: 4
@@ -26,7 +26,7 @@ See: .planning/PROJECT.md (updated 2026-03-29)
 ## Current Position
 
 Phase: 04 (polish-audio) — EXECUTING
-Plan: 2 of 4
+Plan: 3 of 4
 Status: Ready to execute
 Last activity: 2026-03-29
 
@@ -68,6 +68,7 @@ Progress: [░░░░░░░░░░] 0%
 | Phase 03 P02 | 4min | 2 tasks | 6 files |
 | Phase 03 P04 | 3min | 2 tasks | 4 files |
 | Phase 04 P02 | 2min | 2 tasks | 3 files |
+| Phase 04 P03 | 2min | 2 tasks | 3 files |
 
 ## Accumulated Context
 
@@ -104,6 +105,7 @@ Recent decisions affecting current work:
 - [Phase 03]: Progress migration function ensures backward compat with older IndexedDB data
 - [Phase 04]: Stardust particles use box-shadow on pseudo-elements for 6 total sparkle points
 - [Phase 04]: Error overlay uses tree emoji and German child-friendly message
+- [Phase 04]: Export excludes Blobs (only progress+settings) for JSON portability
 
 ### Pending Todos
 
@@ -115,6 +117,6 @@ None yet.
 
 ## Session Continuity
 
-Last session: 2026-03-29T16:17:26.927Z
-Stopped at: Completed 04-02-PLAN.md
+Last session: 2026-03-29T16:17:42.902Z
+Stopped at: Completed 04-03-PLAN.md
 Resume file: None