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/RequirementCandidates.hs

@@ -178,3 +178,58 @@ instance Controller RequirementCandidatesController where
                     , widgets
                     , mStatusFilter = Just "my_queue"
                     }
+
+    action PromoteToRequirementAction { requirementCandidateId } = do
+        candidate <- fetch requirementCandidateId
+        -- Guard: only accepted candidates may be promoted
+        when (candidate.status /= "accepted") do
+            setErrorMessage "Only accepted candidates can be promoted to a requirement"
+            respondWith 422 do
+                redirectTo ShowRequirementCandidateAction { requirementCandidateId }
+        -- Idempotent: if already promoted, redirect to existing requirement
+        case candidate.requirementId of
+            Just rid -> redirectTo ShowRequirementAction { requirementId = rid }
+            Nothing -> do
+                mUser <- currentUserOrNothing
+                let createdBy = fmap (.id) mUser
+                req <- newRecord @Requirement
+                    |> set #title candidate.title
+                    |> set #description candidate.description
+                    |> set #sourceCandidateId requirementCandidateId
+                    |> set #status "active"
+                    |> set #createdBy (fmap (Id . unId) createdBy)
+                    |> createRecord
+                candidate
+                    |> set #requirementId (Just req.id)
+                    |> updateRecord
+                setSuccessMessage "Promoted to requirement"
+                redirectTo ShowRequirementAction { requirementId = req.id }
+
+    action LinkToDecisionAction { requirementCandidateId } = do
+        candidate <- fetch requirementCandidateId
+        -- Guard: only accepted candidates
+        when (candidate.status /= "accepted") do
+            setErrorMessage "Only accepted candidates can be linked to a decision"
+            respondWith 422 do
+                redirectTo ShowRequirementCandidateAction { requirementCandidateId }
+        -- Idempotent: check if a decision already links to this candidate
+        existing <- query @DecisionRecord
+            |> filterWhere (#candidateId, Just requirementCandidateId)
+            |> fetchOneOrNothing
+        case existing of
+            Just dr -> redirectTo ShowDecisionRecordAction { decisionRecordId = dr.id }
+            Nothing -> do
+                mUser <- currentUserOrNothing
+                let decidedBy = fmap (.id) mUser
+                -- Use promoted requirement id if available
+                let mReqId = candidate.requirementId
+                dr <- newRecord @DecisionRecord
+                    |> set #title candidate.title
+                    |> set #rationale candidate.description
+                    |> set #outcome "accepted"
+                    |> set #candidateId (Just requirementCandidateId)
+                    |> set #requirementId mReqId
+                    |> set #decidedBy (fmap (Id . unId) decidedBy)
+                    |> createRecord
+                setSuccessMessage "Decision record created"
+                redirectTo ShowDecisionRecordAction { decisionRecordId = dr.id }