Add host-poller: chassis IPMI/iDRAC + CPU + on-metal drive temps

New third producer container (host-poller) owning the server chassis
subsystem, separate from the SAS-shelf poller:
- services/host_sensors.py: in-band IPMI (ipmitool sdr) for Inlet/Exhaust/etc.
  + CPU package temps from coretemp hwmon
- host_poller.py: own single-instance lock + heartbeat (host_poll keys),
  restart-storm guard, paced; writes jbod:host_sensors + jbod:host_drives
- move host/on-metal drive collection off the SAS poller to host-poller
  (reads jbod:zfs_map for annotation)
- store: generalized lock/meta with a key param; host_sensors + host-poll keys
- mqtt_publisher: publish env/CPU/host-drive temps as entities on the hub
  device (JBOD Monitor)
- Dockerfile host-poller target (ipmitool+smartmontools); compose.infra adds
  host-poller; build.sh gains host-poller/all

compose.infra.yml

@@ -34,6 +34,32 @@ services:
     depends_on:
       - redis
 
+  # Chassis producer: IPMI/iDRAC + CPU coretemp + on-metal drives → Redis.
+  # Separate from the SAS poller (different subsystem); writes host_sensors +
+  # host_drives. The web consumer publishes these on the hub device.
+  host-poller:
+    image: docker.adamksmith.xyz/jbod-host-poller:latest   # pin to a SHA in deploy
+    container_name: jbod-host-poller
+    restart: unless-stopped
+    privileged: true
+    network_mode: host
+    volumes:
+      - /dev:/dev
+      - /sys:/sys:ro
+      - /run/udev:/run/udev:ro
+    environment:
+      - TZ=America/Denver
+      - REDIS_HOST=127.0.0.1
+      - REDIS_PORT=6379
+      - REDIS_DB=0
+      - HOST_POLL_INTERVAL=120
+      - POLL_DRIVE_GAP=0.5
+      - POLL_CONCURRENCY=1
+      - POLL_STARTUP_JITTER=10
+      - POLL_DATA_TTL=900
+    depends_on:
+      - redis
+
   redis:
     image: redis:7-alpine
     container_name: jbod-redis