Bump mcdsl to f94c4b1 for $PORT env var support

Update mcdsl from v1.0.0 to the port-env-support branch tip, which
adds automatic $PORT environment variable support to the config
package. Adapt grpcserver.New call to the updated signature that now
accepts an *Options parameter (pass nil for default behavior).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/grpcserver/server.go

@@ -65,7 +65,7 @@ type Server struct {
 //
 // If certFile or keyFile is empty, TLS is skipped (for testing only).
 func New(certFile, keyFile string, deps Deps, logger *slog.Logger) (*Server, error) {
-	srv, err := mcdslgrpc.New(certFile, keyFile, deps.Authenticator, methodMap(), logger)
+	srv, err := mcdslgrpc.New(certFile, keyFile, deps.Authenticator, methodMap(), logger, nil)
 	if err != nil {
 		return nil, err
 	}