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>

Application/Schema.sql

@@ -205,3 +205,61 @@ CREATE INDEX impl_change_refs_decision_id_idx ON implementation_change_reference
 
 -- Back-reference: which candidate was promoted to a requirement (Phase 3)
 ALTER TABLE requirement_candidates ADD COLUMN requirement_id UUID REFERENCES requirements(id) ON DELETE SET NULL;
+
+-- Deployment records — connect decisions to deployed versions (Phase 4)
+CREATE TABLE deployment_records (
+    id UUID DEFAULT uuid_generate_v4() PRIMARY KEY NOT NULL,
+    impl_ref_id UUID REFERENCES implementation_change_references(id) ON DELETE SET NULL,
+    decision_id UUID NOT NULL REFERENCES decision_records(id) ON DELETE RESTRICT,
+    version_ref TEXT NOT NULL,
+    deployed_at TIMESTAMP WITH TIME ZONE DEFAULT now() NOT NULL,
+    deployed_by UUID REFERENCES users(id),
+    notes TEXT,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT now() NOT NULL
+);
+
+CREATE INDEX deployment_records_decision_id_idx ON deployment_records (decision_id);
+CREATE INDEX deployment_records_deployed_at_idx ON deployment_records (deployed_at DESC);
+
+-- Outcome signals — append-only observation of widget behaviour post-deployment (Phase 4)
+CREATE TABLE outcome_signals (
+    id UUID DEFAULT uuid_generate_v4() PRIMARY KEY NOT NULL,
+    widget_id UUID NOT NULL REFERENCES widgets(id) ON DELETE CASCADE,
+    deployment_id UUID NOT NULL REFERENCES deployment_records(id) ON DELETE CASCADE,
+    signal_type TEXT NOT NULL,
+    value NUMERIC,
+    observed_at TIMESTAMP WITH TIME ZONE DEFAULT now() NOT NULL
+);
+
+CREATE INDEX outcome_signals_widget_id_idx ON outcome_signals (widget_id);
+CREATE INDEX outcome_signals_deployment_id_idx ON outcome_signals (deployment_id);
+CREATE INDEX outcome_signals_observed_at_idx ON outcome_signals (observed_at DESC);
+
+CREATE OR REPLACE FUNCTION prevent_outcome_signal_mutation()
+RETURNS TRIGGER AS $$
+BEGIN
+    RAISE EXCEPTION 'outcome_signals is append-only: UPDATE and DELETE are not permitted';
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER outcome_signals_no_update
+    BEFORE UPDATE ON outcome_signals
+    FOR EACH ROW EXECUTE FUNCTION prevent_outcome_signal_mutation();
+
+CREATE TRIGGER outcome_signals_no_delete
+    BEFORE DELETE ON outcome_signals
+    FOR EACH ROW EXECUTE FUNCTION prevent_outcome_signal_mutation();
+
+-- Change evaluations — one score per deployment (Phase 4)
+CREATE TABLE change_evaluations (
+    id UUID DEFAULT uuid_generate_v4() PRIMARY KEY NOT NULL,
+    deployment_id UUID NOT NULL REFERENCES deployment_records(id) ON DELETE CASCADE,
+    decision_id UUID REFERENCES decision_records(id) ON DELETE SET NULL,
+    score SMALLINT NOT NULL CHECK (score BETWEEN 1 AND 5),
+    rationale TEXT NOT NULL,
+    evaluated_by UUID REFERENCES users(id),
+    evaluated_at TIMESTAMP WITH TIME ZONE DEFAULT now() NOT NULL,
+    UNIQUE (deployment_id)
+);
+
+CREATE INDEX change_evaluations_deployment_id_idx ON change_evaluations (deployment_id);