Add cap_sys_admin to Sunshine for KMS capture on Wayland

Enables KMS capture method which bypasses the XDG portal for screen
capture. Required for proper mouse/keyboard input on KDE Plasma Wayland.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: shanemcd

mybox/Containerfile

@@ -202,4 +202,7 @@ EOF
     systemctl enable cockpit.socket
     systemctl enable apcupsd
     systemctl enable shairport-sync
+
+    # Sunshine: Enable KMS capture for Wayland (requires cap_sys_admin)
+    setcap cap_sys_admin+p /usr/bin/sunshine
 EORUN