feat: no-nginx frontend, host nginx config, configurable ports

- Frontend: remove nginx, use serve for static files
- Frontend: add Projects/Milestones/Notifications pages
- Frontend: fix auth endpoint to match backend (/auth/token)
- docker-compose: configurable ports via env vars, reduce frontend resources
- Add nginx-host.conf.example for host-level reverse proxy
- Add .env.example
- Update README with deployment architecture

.env.example

@@ -0,0 +1,15 @@
+# MySQL
+MYSQL_ROOT_PASSWORD=harborforge_root
+MYSQL_DATABASE=harborforge
+MYSQL_USER=harborforge
+MYSQL_PASSWORD=harborforge_pass
+MYSQL_PORT=3306
+
+# Backend
+SECRET_KEY=change_me_in_production
+LOG_LEVEL=INFO
+BACKEND_PORT=8000
+
+# Frontend
+FRONTEND_PORT=3000
+VITE_API_BASE=/api