docs(04-03): complete SSE payload signing plan

- SUMMARY.md with self-check passed
- STATE.md updated to plan 3/3 complete, 100% progress
- ROADMAP.md and REQUIREMENTS.md updated (SECU-04 complete)
- deferred-items.md documents pre-existing test failures from Plan 02

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

.planning/STATE.md

@@ -3,15 +3,15 @@ gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
 status: in-progress
-stopped_at: Completed 04-01-PLAN.md
-last_updated: "2026-03-11T19:08:55Z"
-last_activity: 2026-03-11 -- Completed 04-01 (Security service foundation)
+stopped_at: Completed 04-03-PLAN.md
+last_updated: "2026-03-11T19:29:30Z"
+last_activity: 2026-03-11 -- Completed 04-03 (SSE payload signing)
 progress:
   total_phases: 4
-  completed_phases: 3
+  completed_phases: 4
   total_plans: 12
-  completed_plans: 10
-  percent: 83
+  completed_plans: 12
+  percent: 100
 ---
 
 # Project State
@@ -26,11 +26,11 @@ See: .planning/PROJECT.md (updated 2026-03-11)
 ## Current Position
 
 Phase: 4 of 4 (Security)
-Plan: 1 of 3 in current phase (Security service foundation)
-Status: Phase 04 in progress, Plan 01 complete
-Last activity: 2026-03-11 -- Completed 04-01 (Security service foundation)
+Plan: 3 of 3 in current phase (SSE payload signing)
+Status: Phase 04 complete, all plans done
+Last activity: 2026-03-11 -- Completed 04-03 (SSE payload signing)
 
-Progress: [████████░░] 83%
+Progress: [██████████] 100%
 
 ## Performance Metrics
 
@@ -60,6 +60,7 @@ Progress: [████████░░] 83%
 | Phase 03 P01 | 15min | 2 tasks | 15 files |
 | Phase 03 P02 | 32min | 2 tasks | 7 files |
 | Phase 04 P01 | 12min | 1 tasks | 15 files |
+| Phase 04 P03 | 17min | 1 tasks | 4 files |
 
 ## Accumulated Context
 
@@ -106,6 +107,8 @@ Recent decisions affecting current work:
 - [Phase 04]: JDK 17 built-in Ed25519 KeyPairGenerator (no Bouncy Castle dependency needed)
 - [Phase 04]: TestSecurityConfig as @Configuration in test sources for automatic @SpringBootTest scanning
 - [Phase 04]: InitializingBean pattern for fail-fast bootstrap token validation on startup
+- [Phase 04]: Signed payload parsed to JsonNode for correct SseEmitter serialization (avoids double-quoting)
+- [Phase 04]: SseSigningIT adapted to Plan 02 security layer (bootstrap token + JWT auth)
 
 ### Pending Todos
 
@@ -120,6 +123,6 @@ None yet.
 
 ## Session Continuity
 
-Last session: 2026-03-11T19:08:55Z
-Stopped at: Completed 04-01-PLAN.md
-Resume file: .planning/phases/04-security/04-02-PLAN.md
+Last session: 2026-03-11T19:29:30Z
+Stopped at: Completed 04-03-PLAN.md
+Resume file: All plans complete