Add /api/health and harden Docker deploy script for API route rollout.

404 on /api/ai indicates stale container; deploy script now uses --no-cache, stops PM2/port conflicts, and verifies /api/health.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/api/health/route.ts

@@ -0,0 +1,8 @@
+export async function GET() {
+  return Response.json({
+    ok: true,
+    service: "zhimingge",
+    apiAi: true,
+    build: "dba0245+",
+  });
+}