Drop assets binding from app wrangler config

Assets-only Workers (no `main` script) cannot declare an assets
binding — there is no Worker to bind it to. The binding was left over
from the recent removal of the SPA-fallback worker and broke deploys
with `Cannot use assets with a binding in an assets-only Worker`.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: bchapuis

apps/app/wrangler.jsonc

@@ -5,7 +5,6 @@
 
   // Static assets configuration with native SPA fallback
   "assets": {
-    "binding": "ASSETS",
     "directory": "./dist",
     "not_found_handling": "single-page-application"
   }