feat: migrate to Cloudflare Workers with icon and version upload

Replace Express/SQLite and web/ with frontend/, worker/, and wrangler deploy. Add optional app icon upload, date-based app_version, and build-app workflow input.

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

frontend/tsconfig.app.tsbuildinfo

@@ -0,0 +1 @@
+{"root":["./src/app.tsx","./src/main.tsx","./src/vite-env.d.ts","./src/api/client.ts","./src/components/layout.tsx","./src/lib/version.ts","./src/pages/buildlist.tsx","./src/pages/jobstatus.tsx","./src/pages/upload.tsx"],"version":"5.6.3"}