fix(nvidia): load ib_umad and install nvlsm/libnvidia-nscq for NVL5 fabric

The NVSwitch-detection fix (983f41a) was necessary but not sufficient on
HGX B200 (Kaytus KR9288-X3): ExecCondition now correctly runs fabricmanager,
but nvidia-fabricmanager-start.sh then aborts with "Kernel module ib_umad
has not been loaded" on this NVL5+ board, leaving the fabric stuck in
"In Progress" and cascading into failed dcgmi diag/NVBandwidth/NCCL/Validate
GPU SAT tasks (confirmed via support bundle 20260729-165331).

Neither nvidia-fabricmanager nor DCGM declare the NVLink5 support packages
as apt dependencies (checked against the cuda-repo Packages index directly):
ib_umad must be modprobed before FM starts, nvlsm (InfiniBand Subnet Manager)
is launched internally by FM's own start script once present, and DCGM
dlopens libnvidia-nscq at runtime for NVSwitch health monitoring.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

iso/overlay/etc/systemd/system/nvidia-fabricmanager.service.d/bee-nvswitch-check.conf

@@ -7,3 +7,10 @@ After=bee-nvidia.service
 # Skip fabricmanager on systems without NVSwitch hardware.
 # ExecCondition exits 1-254 → unit is silently skipped (inactive, not failed).
 ExecCondition=/usr/local/bin/bee-check-nvswitch
+
+# On NVL5+ systems (e.g. HGX B200) nvidia-fabricmanager-start.sh polls for an
+# Infiniband device before starting FM and refuses to start if "ib_umad" isn't
+# loaded, even though mlx5_ib/ib_core/ib_uverbs already are — nothing else on
+# the live ISO triggers its autoload. Load it explicitly; "-" keeps this from
+# failing the unit on older HGX generations without an ib_umad module.
+ExecStartPre=-/sbin/modprobe ib_umad