fix: resolve build compilation, types, and setup errors

[mrnetwork0001]

This PR resolves several out-of-the-box build and compilation issues in the template, allowing npm run build to complete successfully:

1. SDK Dependency & Utilities: Added missing @circle-fin/developer-controlled-wallets dependency, implemented developer-controlled-wallets-client.ts to initialize the client, and implemented the missing app/api/wallet/route.ts endpoint for wallet creation.
2. Webhook Type Fix: Fetched the status column in the Supabase select query in app/api/webhooks/circle/route.ts to resolve a TypeScript type mismatch on existing.status.
3. Tailwind v4 Integration: Switched TS moduleResolution to "bundler" in tsconfig.json to properly resolve Tailwind CSS v4's .d.mts exports. Updated darkMode strategy shape in tailwind.config.ts, and replaced the deprecated safelist JS config with CSS-native @source inline(...) directives in app/globals.css.
4. Supabase Client Fallbacks: Provided fallback placeholder strings for Supabase URL and Anon key in both the client/server Supabase utilities to prevent build-time static page prerendering crashes when environment credentials are not yet defined.