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/Controller/Hubs.hs

@@ -6,6 +6,7 @@ import Web.View.Hubs.Show
 import Web.View.Hubs.New
 import Web.View.Hubs.Edit
 import Web.View.Hubs.TriageDashboard
+import Web.View.Hubs.GovernanceDashboard
 import Generated.Types
 import IHP.Prelude
 import IHP.ControllerPrelude
@@ -110,3 +111,48 @@ instance Controller HubsController where
             , recentEscalations
             , allAnnotations
             }
+
+    action GovernanceDashboardAction { hubId } = autoRefresh do
+        hub     <- fetch hubId
+        widgets <- query @Widget
+            |> filterWhere (#hubId, hubId)
+            |> fetch
+        let widgetIds = map (.id) widgets
+
+        -- All requirements whose source candidate is in this hub's widgets
+        allCandidates <- query @RequirementCandidate
+            |> filterWhereIn (#sourceWidgetId, widgetIds)
+            |> fetch
+        let acceptedCandidateIds = map (.id) (filter (\c -> c.status == "accepted") allCandidates)
+
+        allRequirements <- query @Requirement
+            |> filterWhereIn (#sourceCandidateId, acceptedCandidateIds)
+            |> fetch
+
+        -- Recent decisions (last 20) — scoped to this hub's requirements
+        let requirementIds = map (.id) allRequirements
+        recentDecisions <- query @DecisionRecord
+            |> filterWhereIn (#requirementId, map Just requirementIds)
+            |> orderByDesc #decidedAt
+            |> limit 20
+            |> fetch
+
+        -- All hub decisions (for outcome counts)
+        allDecisions <- query @DecisionRecord
+            |> filterWhereIn (#requirementId, map Just requirementIds)
+            |> fetch
+
+        -- All annotations for traceability coverage
+        allAnnotations <- query @Annotation
+            |> filterWhereIn (#widgetId, widgetIds)
+            |> fetch
+
+        render GovernanceDashboardView
+            { hub
+            , widgets
+            , allCandidates
+            , allRequirements
+            , recentDecisions
+            , allDecisions
+            , allAnnotations
+            }