Enhance WHMCS integration with mTLS support and product mapping features. Added mTLS configuration options, updated API endpoints for mTLS status and fingerprint registration, and implemented product validation API. Updated database schema and documentation accordingly.

deploy/nginx/integration-mtls.conf.example

@@ -0,0 +1,17 @@
+# Example nginx snippet for GameCloud WHMCS integration mTLS
+# Place inside the server {} block that proxies to the API upstream.
+
+ssl_client_certificate /etc/ssl/gamecloud/integration-ca.crt;
+ssl_verify_client optional;
+
+location /api/v1/integrations/whmcs/ {
+    proxy_pass http://gamecloud_api;
+    proxy_set_header Host $host;
+    proxy_set_header X-Real-IP $remote_addr;
+    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+    proxy_set_header X-Forwarded-Proto $scheme;
+
+    # OpenSSL 1.1.1+ / nginx 1.15.3+
+    proxy_set_header X-HGC-Client-Cert-Fingerprint $ssl_client_fingerprint;
+    proxy_set_header X-HGC-Client-Cert-Subject $ssl_client_s_dn;
+}