fix: documentation

README.md

@@ -56,8 +56,8 @@ cd frontend && npm install && npm run dev
 docker compose up --build
 ```
 
-- **Frontend**: http://localhost:3000 (Nginx; `/api/*` proxied to backend).
-- **Backend**: http://localhost:8080 (Express).
+- **Frontend**: <http://localhost:3000> (Nginx; `/api/*` proxied to backend).
+- **Backend**: <http://localhost:8080> (Express).
 
 Environment variables (backend service):
 
@@ -74,6 +74,18 @@ For self-hosting (e.g. Tailscale/HTTPS): set `CORS_ORIGIN` to your frontend URL;
 
 ## Scripts
 
+## Contribute
+
+For contribution guidelines, see:
+
+- [ARCHITECTURE.md](ARCHITECTURE.md)
+- [PERFORMANCE_IMPROVEMENTS.md](PERFORMANCE_IMPROVEMENTS.md)
+- [QUICKSTART_FOR_JUNIORS.md](QUICKSTART_FOR_JUNIORS.md)
+- [CONTRIBUTING.md](CONTRIBUTING.md)
+- [CODE_REVIEW_CHECKLIST.md](CODE_REVIEW_CHECKLIST.md)
+
+*Thank you for contributing!*
+
 | Command | Description |
 |--------|-------------|
 | `cd frontend && npm run dev` | Vite dev server. |