feat: Add SECURE_SITE configuration and reverse proxy documentation

- Introduced the SECURE_SITE environment variable to control cookie security settings based on deployment context.
- Updated Dockerfile to log SECURE_SITE status during application startup.
- Enhanced documentation with a new guide on reverse proxy configuration, detailing the use of SECURE_SITE for secure cookie handling.
- Adjusted authentication and email services to utilize SECURE_SITE for secure connections.
- Updated frontend components to set cookie security based on the current protocol.

Dockerfile

@@ -132,6 +132,7 @@ set -e
 
 echo "Starting Palmr Application..."
 echo "Storage Mode: \${ENABLE_S3:-false}"
+echo "Secure Site: \${SECURE_SITE:-false}"
 echo "Database: SQLite"
 
 # Set global environment variables