feat: PWA Phase 2 — push notifications

Add web push notification support: push_subscriptions table (migration
0007), VAPID-based push service, subscribe/unsubscribe API routes, SW
push+notificationclick handlers, and subscribe UI on account page.
Triggers: new version uploaded (all project members) and version
approved/rejected (uploader).

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

apps/api/package.json

@@ -16,6 +16,7 @@
     "drizzle-orm": "^0.44",
     "fflate": "^0.8.2",
     "hono": "^4",
-    "resend": "^6.10.0"
+    "resend": "^6.10.0",
+    "web-push": "^3.6.7"
   }
 }