Add RDP user consent popup before screen sharing

When rdp_start arrives, agent first spawns a WPF consent dialog in the
user session (via schtasks). User has 30s to accept or deny. On deny,
agent sends rdp_denied to browser which shows "Zugriff abgelehnt".
On accept, screen capture starts as before.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

agent-cs/Program.cs

@@ -19,6 +19,10 @@ internal class Program
                     RunNotification(args.Length > 1 ? args[1] : "");
                     return;
 
+                case "--rdp-consent":
+                    ConsentModeRunner.Run(args.Length > 1 ? args[1] : "");
+                    return;
+
                 case "--rdp-capture":
                     CaptureModeRunner.Run(
                         args.Length > 1 ? args[1] : "",