feat: Add frontend and backend initialization scripts, implement Keycloak and PostgreSQL setup

- Implemented SvelteKit frontend with authentication callback handling.
- Created demo routes and paraglide localization functionality.
- Added health check and entrypoint scripts for backend services.
- Established PostgreSQL and Keycloak initialization scripts with health checks.
- Introduced models for database schema using SQLAlchemy.
- Configured Vite and SvelteKit for development and testing environments.
- Added health check script to verify service statuses and resource usage.
- Created Docker entrypoint scripts for seamless service startup.

frontend/.env.example

@@ -0,0 +1,5 @@
+# Environment variables para frontend
+PUBLIC_API_URL=http://localhost:8000
+PUBLIC_KEYCLOAK_URL=http://localhost:8080
+PUBLIC_KEYCLOAK_REALM=master
+PUBLIC_KEYCLOAK_CLIENT_ID=anexo76-frontend