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/FrontController.hs

@@ -11,6 +11,10 @@ import Web.Controller.Hubs ()
 import Web.Controller.Widgets ()
 import Web.Controller.InteractionEvents ()
 import Web.Controller.Annotations ()
+import Web.Controller.AnnotationThreads ()
+import Web.Controller.RequirementCandidates ()
+import Web.Controller.Requirements ()
+import Web.Controller.DecisionRecords ()
 import Web.Controller.Sessions ()
 
 instance FrontController WebApplication where
@@ -20,6 +24,10 @@ instance FrontController WebApplication where
         , parseRoute @WidgetsController
         , parseRoute @InteractionEventsController
         , parseRoute @AnnotationsController
+        , parseRoute @AnnotationThreadsController
+        , parseRoute @RequirementCandidatesController
+        , parseRoute @RequirementsController
+        , parseRoute @DecisionRecordsController
         ]
 
 instance InitControllerContext WebApplication where
@@ -45,6 +53,9 @@ defaultLayout inner = [hsx|
                 <a href={HubsAction} class="font-semibold text-indigo-600">inter-hub</a>
                 <a href={HubsAction} class="text-sm text-gray-600 hover:text-gray-900">Hubs</a>
                 <a href={WidgetsAction} class="text-sm text-gray-600 hover:text-gray-900">Widgets</a>
+                <a href={RequirementCandidatesAction} class="text-sm text-gray-600 hover:text-gray-900">Candidates</a>
+                <a href={RequirementsAction} class="text-sm text-gray-600 hover:text-gray-900">Requirements</a>
+                <a href={DecisionRecordsAction} class="text-sm text-gray-600 hover:text-gray-900">Decisions</a>
                 <div class="ml-auto">
                     <a href={DeleteSessionAction} class="text-sm text-gray-500 hover:text-gray-700">Sign out</a>
                 </div>