chore: update gateway URL configuration for staging environment

- Changed GW_URL and GwUrl in frontoffice-deployment.yaml and Dockerfile to use the internal service URL http://cms-svc:8080 for the staging environment.
- Enhanced ConfigureServices to handle HTTP/1.1 for gRPC when using the internal service URL, ensuring compatibility with Kestrel's requirements.

src/FrontOffice.Main/ConfigureServices.cs

@@ -103,16 +103,28 @@ public static class ConfigureServices
         var baseUrl = ResolveGatewayUrl(configuration)
             ?? throw new InvalidOperationException("Gateway URL is missing. Set GW_URL or GwUrl.");
 
-        // Register optimized HttpClient for gRPC
+        var isHttp = baseUrl.StartsWith("http://", StringComparison.OrdinalIgnoreCase);
+
+        // When the base URL is plain HTTP (e.g. in-cluster http://cms-svc:8080), we must force HTTP/1.1
+        // so that GrpcChannel does not upgrade to h2c and trigger HTTP_1_1_REQUIRED from Kestrel.
+        // For HTTPS the default negotiation is fine.
         services.AddScoped(sp =>
         {
-            var handler = new HttpClientHandler
-            {
-                MaxConnectionsPerServer = 10,
-                AutomaticDecompression = System.Net.DecompressionMethods.GZip | System.Net.DecompressionMethods.Deflate
-            };
+            HttpMessageHandler inner = isHttp
+                ? new SocketsHttpHandler
+                {
+                    MaxConnectionsPerServer = 10,
+                    AutomaticDecompression = System.Net.DecompressionMethods.GZip | System.Net.DecompressionMethods.Deflate,
+                    DefaultRequestVersion = System.Net.HttpVersion.Version11,
+                    DefaultVersionPolicy = System.Net.Http.HttpVersionPolicy.RequestVersionExact
+                }
+                : new HttpClientHandler
+                {
+                    MaxConnectionsPerServer = 10,
+                    AutomaticDecompression = System.Net.DecompressionMethods.GZip | System.Net.DecompressionMethods.Deflate
+                };
 
-            return new HttpClient(new GrpcWebHandler(GrpcWebMode.GrpcWeb, handler))
+            return new HttpClient(new GrpcWebHandler(GrpcWebMode.GrpcWeb, inner))
             {
                 Timeout = TimeSpan.FromMinutes(10),
                 BaseAddress = new Uri(baseUrl)