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/Requirements.hs

@@ -0,0 +1,25 @@
+module Web.Controller.Requirements where
+
+import Web.Types
+import Web.View.Requirements.Index
+import Web.View.Requirements.Show
+import Generated.Types
+import IHP.Prelude
+import IHP.ControllerPrelude
+
+instance Controller RequirementsController where
+    beforeAction = ensureIsUser
+
+    action RequirementsAction = do
+        requirements <- query @Requirement |> orderByDesc #createdAt |> fetch
+        candidates   <- query @RequirementCandidate |> fetch
+        render IndexView { requirements, candidates }
+
+    action ShowRequirementAction { requirementId } = do
+        requirement <- fetch requirementId
+        candidate   <- fetch requirement.sourceCandidateId
+        widget      <- fetch candidate.sourceWidgetId
+        mDecision   <- query @DecisionRecord
+            |> filterWhere (#requirementId, Just requirementId)
+            |> fetchOneOrNothing
+        render ShowView { requirement, candidate, widget, mDecision }