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.

frontend/src/api/types.ts

@@ -180,6 +180,18 @@ export interface ScanResult {
   created: Record<string, number>;
 }
 
+export interface SearchResultItem {
+  type: "vehicle" | "booking" | "data_quality_issue" | "section";
+  label: string;
+  detail: string;
+  link: string;
+}
+
+export interface SearchResponse {
+  query: string;
+  results: SearchResultItem[];
+}
+
 export interface MergeCustomersRequest {
   survivor_ref: string;
   field_overrides?: Record<string, string>;
@@ -218,6 +230,28 @@ export interface KnowledgeHealth {
   document_count: number;
 }
 
+export interface N8nIntegrationStatus {
+  configured: boolean;
+  dispatch_enabled: boolean;
+  state: "disabled" | "unavailable" | "degraded" | "operational" | "no_evidence";
+  pending: number;
+  delivering: number;
+  failed: number;
+  succeeded: number;
+  latest_success_at: string | null;
+  latest_failure_at: string | null;
+}
+
+export interface McpHubIntegrationStatus {
+  registration_enabled: boolean;
+  state: "not_configured" | "configured";
+}
+
+export interface IntegrationStatus {
+  n8n: N8nIntegrationStatus;
+  mcp_hub: McpHubIntegrationStatus;
+}
+
 export interface AuditEvent {
   id: string;
   actor_type: string;