Add GPU passthrough, fan control, and bay mapping scripts

- scripts/build-bay-map.sh: maps physical drive bays to /dev/disk/by-id paths
- scripts/gpu-passthrough-setup.sh: configures IOMMU + vfio-pci for two Quadro P2200s
- scripts/fan-control.sh: ipmitool daemon to prevent iDRAC from running fans at
  100% due to non-Dell PCIe cards; adjusts speed by inlet temperature
- scripts/fan-control.service: systemd unit for fan-control.sh

https://claude.ai/code/session_01TxTSnxDjgEVuNztdsWQjMD

scripts/fan-control.service

@@ -0,0 +1,19 @@
+[Unit]
+Description=Dell R730xd fan speed control (third-party GPU)
+# iDRAC sets fans to 100% when non-Dell PCIe cards are detected.
+# This service overrides that and manages fan speed by inlet temperature.
+After=network.target
+# Restart if ipmitool fails transiently (e.g. iDRAC busy at boot)
+StartLimitIntervalSec=60
+StartLimitBurst=5
+
+[Service]
+Type=simple
+ExecStart=/usr/local/sbin/fan-control.sh
+# On stop, re-enable iDRAC auto control so fans are safe if service is removed
+ExecStop=/usr/local/sbin/fan-control.sh --auto
+Restart=on-failure
+RestartSec=10
+
+[Install]
+WantedBy=multi-user.target