ci(deploy): configure workers static assets

[Tuxedolphin]

Summary

• add frontend/wrangler.jsonc for Cloudflare Workers Static Assets
• update deployment docs from Pages Git integration to Workers Builds
• ignore Wrangler local cache directories

Deployment settings

• Path: frontend
• Build command: pnpm install --frozen-lockfile && pnpm build
• Deploy command: npx wrangler deploy
• VITE_API_BASE_URL can remain unset until the backend is deployed

Verification

• pnpm build
• npx --yes wrangler@latest deploy --dry-run
• git diff --check
• staged diff reviewed for tokens and generated attribution strings