docs(04-01): complete audio system plan

- Add 04-01-SUMMARY.md with execution results
- Update STATE.md with position, decisions, metrics
- Update ROADMAP.md with plan progress
- Mark AUDI-01 through AUDI-05 complete in REQUIREMENTS.md

.planning/STATE.md

@@ -3,14 +3,14 @@ gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
 status: executing
-stopped_at: Completed 04-03-PLAN.md
-last_updated: "2026-03-29T16:17:42.908Z"
+stopped_at: Completed 04-01-PLAN.md
+last_updated: "2026-03-29T16:19:56.987Z"
 last_activity: 2026-03-29
 progress:
   total_phases: 4
   completed_phases: 3
   total_plans: 19
-  completed_plans: 17
+  completed_plans: 18
   percent: 0
 ---
 
@@ -26,7 +26,7 @@ See: .planning/PROJECT.md (updated 2026-03-29)
 ## Current Position
 
 Phase: 04 (polish-audio) — EXECUTING
-Plan: 3 of 4
+Plan: 4 of 4
 Status: Ready to execute
 Last activity: 2026-03-29
 
@@ -69,6 +69,7 @@ Progress: [░░░░░░░░░░] 0%
 | Phase 03 P04 | 3min | 2 tasks | 4 files |
 | Phase 04 P02 | 2min | 2 tasks | 3 files |
 | Phase 04 P03 | 2min | 2 tasks | 3 files |
+| Phase 04 P01 | 4min | 2 tasks | 9 files |
 
 ## Accumulated Context
 
@@ -106,6 +107,8 @@ Recent decisions affecting current work:
 - [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
+- [Phase 04]: speechEnabled defaults to false (opt-in), audioEnabled defaults to true (opt-out)
+- [Phase 04]: AudioContext lazy init on first user interaction for autoplay policy compliance
 
 ### Pending Todos
 
@@ -117,6 +120,6 @@ None yet.
 
 ## Session Continuity
 
-Last session: 2026-03-29T16:17:42.902Z
-Stopped at: Completed 04-03-PLAN.md
+Last session: 2026-03-29T16:19:56.980Z
+Stopped at: Completed 04-01-PLAN.md
 Resume file: None