Fix wrangler.jsonc for Cloudflare Workers deployment

- assets.directory: ./dist/public → ./dist (Astro static output goes to
  dist/ directly, not a public subdirectory)
- not_found_handling: single-page-application → 404-page (site is
  pre-rendered static HTML, SPA mode would serve index.html for all 404s
  instead of the proper 404 page)

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

wrangler.jsonc

@@ -3,9 +3,9 @@
   "main": "src/worker.ts",
   "compatibility_date": "2025-12-21",
   "assets": {
-    "directory": "./dist/public",
+    "directory": "./dist",
     "binding": "ASSETS",
-    "not_found_handling": "single-page-application"
+    "not_found_handling": "404-page"
   },
   "vars": {
     "CONTACT_FROM_EMAIL": "info@highlandgrouprda.org.uk",