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/Controller/Hubs.hs

@@ -8,6 +8,7 @@ import Web.View.Hubs.Edit
 import Web.View.Hubs.TriageDashboard
 import Web.View.Hubs.GovernanceDashboard
 import Web.View.Hubs.AntifragilityDashboard
+import Web.View.Hubs.AgentAuditDashboard
 import Generated.Types
 import IHP.Prelude
 import IHP.ControllerPrelude
@@ -219,3 +220,11 @@ instance Controller HubsController where
             , regressionWidgetIds
             , recurrenceLeaderboard
             }
+    action AgentAuditDashboardAction { hubId } = autoRefresh do
+        hub       <- fetch hubId
+        proposals <- query @AgentProposal
+            |> orderByDesc #createdAt
+            |> fetch
+        reviews   <- query @AgentReviewRecord |> fetch
+        widgets   <- query @Widget |> fetch
+        render AgentAuditDashboardView { hub, proposals, reviews, widgets }