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.

.devdbrc

@@ -0,0 +1,6 @@
+[
+  {
+    "type": "sqlite",
+    "path": "c:\\xampp\\htdocs\\SaaS-PDF\\backend\\data\\saas_pdf.db"
+  }
+]