Serve app static assets without worker round-trip

Drop the SPA-fallback worker in favor of the assets binding's native
single-page-application not_found_handling. Every request previously
went through the worker first, which added cold-start latency that
caused crawlers (e.g. Ahrefs) to time out fetching robots.txt. Also
disallow indexing on app.dafthunk.com — the subdomain is the auth-gated
application UI and has no public content to crawl.

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

Author: bchapuis

apps/app/public/robots.txt

@@ -1,4 +1,2 @@
 User-agent: *
-Allow: /$
-Allow: /share/
 Disallow: /

apps/app/worker/index.ts

@@ -2,12 +2,11 @@
   "$schema": "node_modules/wrangler/config-schema.json",
   "name": "dafthunk-app",
   "compatibility_date": "2025-11-17",
-  "main": "./worker/index.ts",
 
-  // Static assets configuration
+  // Static assets configuration with native SPA fallback
   "assets": {
     "binding": "ASSETS",
     "directory": "./dist",
-    "run_worker_first": true
+    "not_found_handling": "single-page-application"
   }
 }