feat(P4): IHF Phase 4 complete — Outcome Observation and Antifragility Loop

Closes the IHF improvement loop. Full antifragility chain now traversable:
Widget → Annotation → Candidate → Requirement → Decision → Deployment → OutcomeSignal

New artifacts:
- DeploymentRecord (immutable, links DecisionRecord to a deployed version)
- OutcomeSignal (append-only; DB trigger prevents UPDATE/DELETE)
- ChangeEvaluation (one-per-deployment; UNIQUE constraint; 1–5 score)

New capabilities:
- DeploymentRecordsController (index, show, new, create)
- RecordOutcomeSignalAction — capture improved/regressed/neutral/inconclusive signals
- Pre/post comparison panel on deployment show (±30-day event/annotation counts)
- Regression detection — improved signal followed by high/critical annotation
- ChangeEvaluation — idempotent score+rationale per deployment
- Recurrence tracking — cycle count per widget, leaderboard
- AntifragilityDashboardAction (autoRefresh, 5 panels) per hub
- Phase 4 integration tests (T01–T08 logic coverage)
- docs/phase4-summary.md; SCOPE.md updated to Phase 4 complete

State Hub: workstream 07e9c860 → completed

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

Web/View/Hubs/Show.hs

@@ -37,6 +37,10 @@ instance View ShowView where
                        class="text-sm border border-purple-300 text-purple-700 px-3 py-1.5 rounded hover:bg-purple-50">
                         Governance Dashboard
                     </a>
+                    <a href={AntifragilityDashboardAction { hubId = hub.id }}
+                       class="text-sm border border-green-300 text-green-700 px-3 py-1.5 rounded hover:bg-green-50">
+                        Antifragility
+                    </a>
                     <a href={EditHubAction { hubId = hub.id }}
                        class="text-sm border border-gray-300 px-3 py-1.5 rounded hover:bg-gray-50">
                         Edit