feat(P5): IHF Phase 5 complete — agent-assisted distillation

Adds bounded AI support to the IHF governance loop. All AI outputs are
attributed (model_ref), reviewable (AgentReviewRecord), and reversible.
No autonomous decisions; no silent requirement promotion.

- T01: Schema — agent_proposals, agent_review_records,
  confidence_annotations (migration 1743379200)
- T02: AgentProposalsController (index/show/accept/reject, idempotent
  review guard), global nav "Agent" link
- T03: SummarizeClusterAction — Claude API cluster summary on widget show
- T04: DraftRequirementAction — AI requirement draft; acceptance creates
  RequirementCandidate (human-gated)
- T05: DetectDuplicatesAction — duplicate_flag proposal on candidate show
- T06: DetectPolicySensitivityAction — policy_flag with
  ConfidenceAnnotations per concern scope
- T07: ProposeImplementationAction — impl_proposal from decision show
- T08: AgentAuditDashboardAction — autoRefresh; KPI row, unreviewed queue,
  recent proposals, attribution log matrix
- T09: integration tests, SCOPE.md updated, phase5-summary.md, flake.nix
  adds http-conduit/aeson/string-conversions

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

Web/Types.hs

@@ -26,6 +26,7 @@ data HubsController
     | TriageDashboardAction          { hubId :: !(Id Hub) }
     | GovernanceDashboardAction      { hubId :: !(Id Hub) }
     | AntifragilityDashboardAction   { hubId :: !(Id Hub) }
+    | AgentAuditDashboardAction      { hubId :: !(Id Hub) }
     deriving (Eq, Show, Data)
 
 data WidgetsController
@@ -33,8 +34,10 @@ data WidgetsController
     | NewWidgetAction
     | ShowWidgetAction   { widgetId :: !(Id Widget)  }
     | CreateWidgetAction
-    | EditWidgetAction   { widgetId :: !(Id Widget)  }
-    | UpdateWidgetAction { widgetId :: !(Id Widget)  }
+    | EditWidgetAction            { widgetId :: !(Id Widget)  }
+    | UpdateWidgetAction          { widgetId :: !(Id Widget)  }
+    | SummarizeClusterAction      { widgetId :: !(Id Widget)  }
+    | DraftRequirementAction      { widgetId :: !(Id Widget)  }
     deriving (Eq, Show, Data)
 
 data InteractionEventsController
@@ -67,8 +70,10 @@ data RequirementCandidatesController
     | UpdateTriageStatusAction         { requirementCandidateId :: !(Id RequirementCandidate) }
     | AssignReviewerAction             { requirementCandidateId :: !(Id RequirementCandidate) }
     | MyQueueAction
-    | PromoteToRequirementAction       { requirementCandidateId :: !(Id RequirementCandidate) }
-    | LinkToDecisionAction             { requirementCandidateId :: !(Id RequirementCandidate) }
+    | PromoteToRequirementAction        { requirementCandidateId :: !(Id RequirementCandidate) }
+    | LinkToDecisionAction              { requirementCandidateId :: !(Id RequirementCandidate) }
+    | DetectDuplicatesAction            { requirementCandidateId :: !(Id RequirementCandidate) }
+    | DetectPolicySensitivityAction     { requirementCandidateId :: !(Id RequirementCandidate) }
     deriving (Eq, Show, Data)
 
 data RequirementsController
@@ -87,6 +92,7 @@ data DecisionRecordsController
     | DeletePolicyReferenceAction       { policyReferenceId :: !(Id PolicyReference) }
     | AddImplementationRefAction        { decisionRecordId :: !(Id DecisionRecord) }
     | DeleteImplementationRefAction     { implementationChangeReferenceId :: !(Id ImplementationChangeReference) }
+    | ProposeImplementationAction       { decisionRecordId :: !(Id DecisionRecord) }
     deriving (Eq, Show, Data)
 
 data DeploymentRecordsController
@@ -98,6 +104,13 @@ data DeploymentRecordsController
     | EvaluateChangeAction            { deploymentRecordId :: !(Id DeploymentRecord) }
     deriving (Eq, Show, Data)
 
+data AgentProposalsController
+    = AgentProposalsAction
+    | ShowAgentProposalAction { agentProposalId :: !(Id AgentProposal) }
+    | AcceptProposalAction    { agentProposalId :: !(Id AgentProposal) }
+    | RejectProposalAction    { agentProposalId :: !(Id AgentProposal) }
+    deriving (Eq, Show, Data)
+
 data SessionsController
     = NewSessionAction
     | CreateSessionAction