feat(P3): IHF Phase 3 complete — Governance and Decision Linkage

Implements the full governance layer:
- Schema: requirements, decision_records, policy_references,
  implementation_change_references; requirement_candidates gets
  requirement_id back-reference
- RequirementsController (index/show; promotion-only create)
- DecisionRecordsController (CRUD + policy/impl ref management)
- GovernanceDashboardAction on HubsController (AutoRefresh)
- PromoteToRequirementAction + LinkToDecisionAction on candidates
- Outcome immutability enforced at controller level (fill excludes outcome)
- Full six-outcome vocabulary with Tailwind color roles
- Integration tests for all Phase 3 paths
- FrontController: registers Phase 2 missing controllers + all Phase 3
- SCOPE.md + docs/phase3-summary.md updated

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

Web/Routes.hs

@@ -22,5 +22,11 @@ instance AutoRoute AnnotationThreadsController
 -- Requirement Candidates
 instance AutoRoute RequirementCandidatesController
 
+-- Requirements (Phase 3)
+instance AutoRoute RequirementsController
+
+-- Decision Records (Phase 3)
+instance AutoRoute DecisionRecordsController
+
 -- Sessions
 instance AutoRoute SessionsController