feat(search): add role-aware backend search and truthful n8n status

Two new endpoints. GET /api/v1/search returns bounded typed results
(vehicle, booking, data-quality-issue, application section) instead of the
frontend guessing routes from regex patterns against public-ref prefixes;
data-quality and manager-only sections are filtered server-side by role,
and customers are deliberately never returned since no customer detail
route exists in this PoC.

GET /api/v1/integrations/status aggregates outbox delivery counts
(pending/delivering/succeeded/failed) into a single truthful n8n state
(disabled/unavailable/degraded/operational/no_evidence) instead of the UI
showing whichever status the single most recent event happened to be in --
a vehicle_status_conflict-style bug where one stale failure or one lucky
success could misreport the dispatcher's actual health.

Also fixes a real config gap this surfaced: MCP_HUB_REGISTRATION_ENABLED
was documented in .env.example but had no corresponding Settings field, so
it was silently ignored by pydantic-settings' extra="ignore" and never
actually read anywhere in the codebase.

backend/tests/test_integration_status.py

@@ -0,0 +1,41 @@
+def test_integration_status_requires_operations_manager(employee_client):
+    response = employee_client.get("/api/v1/integrations/status")
+    assert response.status_code == 403
+
+
+def test_integration_status_requires_authentication(client):
+    response = client.get("/api/v1/integrations/status")
+    assert response.status_code == 401
+
+
+def test_integration_status_reflects_seeded_mixed_outcomes(ops_client):
+    response = ops_client.get("/api/v1/integrations/status")
+    assert response.status_code == 200
+    body = response.json()
+
+    n8n = body["n8n"]
+    assert n8n["dispatch_enabled"] is True
+    assert n8n["succeeded"] >= 1
+    assert n8n["failed"] >= 1
+    # The seed deliberately carries both failed and succeeded events, so a single most-
+    # recent-event read would misreport health -- the aggregate must call this "degraded",
+    # not "operational" or "unavailable".
+    assert n8n["state"] == "degraded"
+    assert n8n["latest_success_at"] is not None
+    assert n8n["latest_failure_at"] is not None
+
+    mcp_hub = body["mcp_hub"]
+    assert mcp_hub["registration_enabled"] is False
+    assert mcp_hub["state"] == "not_configured"
+
+
+def test_integration_status_is_operational_once_all_failed_events_resolved(ops_client):
+    failed = ops_client.get("/api/v1/workflows", params={"status": "failed"}).json()
+    for run in failed:
+        retried = ops_client.post(f"/api/v1/workflows/{run['event_id']}/retry")
+        assert retried.status_code == 200
+
+    response = ops_client.get("/api/v1/integrations/status")
+    body = response.json()["n8n"]
+    assert body["failed"] == 0
+    assert body["state"] == "operational"