feat: Implement CSRF protection and PostgreSQL support

- Added CSRF protection mechanism in the backend with utility functions for token management.
- Introduced a new CSRF route to fetch the active CSRF token for SPA bootstrap flows.
- Updated the auth routes to validate CSRF tokens on sensitive operations.
- Configured PostgreSQL as a database option in the environment settings and Docker Compose.
- Created a new SQLite configuration file for local development.
- Enhanced the API client to automatically attach CSRF tokens to requests.
- Updated various frontend components to utilize the new site origin utility for SEO purposes.
- Modified Nginx configuration to improve redirection and SEO headers.
- Added tests for CSRF token handling in the authentication routes.

.env.example

@@ -56,6 +56,9 @@ SENTRY_ENVIRONMENT=production
 
 # PostgreSQL (production) — leave empty to use SQLite
 DATABASE_URL=
+POSTGRES_DB=dociva
+POSTGRES_USER=dociva
+POSTGRES_PASSWORD=replace-with-strong-postgres-password
 
 # Frontend
 VITE_SITE_DOMAIN=https://dociva.io