feat: add pending vehicle association resolution UI (refs #160)

Backend: Add authenticated endpoints for pending association CRUD
(GET/POST/DELETE /api/email-ingestion/pending). Service methods for
resolving (creates fuel/maintenance record) and dismissing associations.

Frontend: New email-ingestion feature with types, API client, hooks,
PendingAssociationBanner (dashboard), PendingAssociationList, and
ResolveAssociationDialog. Mobile-first responsive with 44px touch
targets and full-screen dialogs on small screens.

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

backend/src/features/email-ingestion/api/email-ingestion.routes.ts

@@ -1,11 +1,12 @@
 /**
- * @ai-summary Resend inbound webhook route registration
- * @ai-context Public endpoint (no JWT auth) with rawBody for signature verification
+ * @ai-summary Resend inbound webhook + user-facing pending association routes
+ * @ai-context Public webhook (no JWT) + authenticated CRUD for pending vehicle associations
  */
 
 import { FastifyPluginAsync } from 'fastify';
 import { EmailIngestionController } from './email-ingestion.controller';
 
+/** Public webhook route - no JWT auth, uses Svix signature verification */
 export const emailIngestionWebhookRoutes: FastifyPluginAsync = async (fastify) => {
   const controller = new EmailIngestionController();
 
@@ -22,3 +23,38 @@ export const emailIngestionWebhookRoutes: FastifyPluginAsync = async (fastify) =
     controller.handleInboundWebhook.bind(controller)
   );
 };
+
+/** Authenticated user-facing routes for pending vehicle associations */
+export const emailIngestionRoutes: FastifyPluginAsync = async (fastify) => {
+  const controller = new EmailIngestionController();
+
+  // GET /api/email-ingestion/pending - List pending associations for authenticated user
+  fastify.get('/email-ingestion/pending', {
+    preHandler: [fastify.authenticate],
+    handler: controller.getPendingAssociations.bind(controller),
+  });
+
+  // GET /api/email-ingestion/pending/count - Get count of pending associations
+  fastify.get('/email-ingestion/pending/count', {
+    preHandler: [fastify.authenticate],
+    handler: controller.getPendingAssociationCount.bind(controller),
+  });
+
+  // POST /api/email-ingestion/pending/:id/resolve - Resolve by selecting vehicle
+  fastify.post<{ Params: { id: string }; Body: { vehicleId: string } }>(
+    '/email-ingestion/pending/:id/resolve',
+    {
+      preHandler: [fastify.authenticate],
+      handler: controller.resolveAssociation.bind(controller),
+    }
+  );
+
+  // DELETE /api/email-ingestion/pending/:id - Dismiss/discard a pending association
+  fastify.delete<{ Params: { id: string } }>(
+    '/email-ingestion/pending/:id',
+    {
+      preHandler: [fastify.authenticate],
+      handler: controller.dismissAssociation.bind(controller),
+    }
+  );
+};