Ubuntu VM102 software-only fallback profile (2026-11-06)

Reason:
- No dedicated hardware encoder can be assigned to Ubuntu.
- VirtIO blob/host-visible trial was unstable and rolled back.

Applied only to box desktop ticket desk-ubuntu-01 (192.168.1.72):
- resolution: 2560x1440
- fps: 30 (was 45)
- bitrate: 20000 kbps (was unset/default)
- backup before FPS change: /home/armbian/vdi-terminal/backups/ubuntu-fps-20261106-161857-626756
- backup before bitrate change: /home/armbian/vdi-terminal/backups/ubuntu-low-latency-20261106-162036-471148

VM102 guest state remains:
- cpu=host, 4 vCPU, 6144 MB
- vga=virtio-gl
- Sunshine capture=kms, encoder=software, ultrafast/zerolatency, 2 threads
- GNOME animations disabled

Expected effect:
- Prevent a 45 FPS client request from building a software-encoder backlog.
- Keep 2K resolution while reducing frame pacing and interaction tail latency.
- This is the best reversible software profile on the current 4-core/no-GPU host; it cannot provide Windows hardware-encoder equivalence.

The ticket change applies on the next Ubuntu connection; an existing Moonlight session must be reconnected to use it.
