feat: add trust_forwarded_proto option for SSL redirect handling in reverse proxy scenarios

When Nginx is behind another proxy server (like CloudFlare or AWS ALB), the force-SSL
feature can cause redirect loops because Nginx sees the connection as plain HTTP
while SSL is already handled upstream. This adds a new boolean option to trust
the X-Forwarded-Proto header from upstream proxies.

Changes:
- Add `trust_forwarded_proto` column to proxy_host table (migration)
- Update model and API schema to support the new boolean field
- Modify force-ssl Nginx template to check X-Forwarded-Proto/X-Forwarded-Scheme
- Add map directives in nginx.conf to validate and sanitize forwarded headers
- Add advanced option toggle in frontend UI with i18n support (EN/ZH)
- Set proxy headers from validated map variables instead of $scheme

This allows administrators to control SSL redirect behavior when Nginx is deployed
behind a TLS-terminating proxy.

docker/rootfs/etc/nginx/nginx.conf

@@ -57,6 +57,18 @@ http {
 		default http;
 	}
 
+	# Handle upstream X-Forwarded-Proto and X-Forwarded-Scheme header
+	map $http_x_forwarded_proto $x_forwarded_proto {
+		"http" "http";
+		"https" "https";
+		default $scheme;
+	}
+	map $http_x_forwarded_scheme $x_forwarded_scheme {
+		"http" "http";
+		"https" "https";
+		default $scheme;
+	} 
+
 	# Real IP Determination
 
 	# Local subnets: