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

services/store.py

@@ -23,9 +23,12 @@ K_SES = "jbod:ses:{}"
 K_ZFS = "jbod:zfs_map"
 K_INVENTORY = "jbod:inventory"
 K_HOST_DRIVES = "jbod:host_drives"
+K_HOST_SENSORS = "jbod:host_sensors"
 K_META = "jbod:poll:meta"
+K_HOST_META = "jbod:host_poll:meta"
 K_LED_QUEUE = "jbod:led:queue"
 K_LOCK = "jbod:poll:lock"
+K_HOST_LOCK = "jbod:host_poll:lock"
 
 
 # ── writes (poller) ─────────────────────────────────────────────────────
@@ -49,9 +52,13 @@ async def set_host_drives(host_drives: list) -> None:
     await cache_set(K_HOST_DRIVES, host_drives, DATA_TTL)
 
 
-async def set_meta(meta: dict) -> None:
+async def set_host_sensors(sensors: dict) -> None:
+    await cache_set(K_HOST_SENSORS, sensors, DATA_TTL)
+
+
+async def set_meta(meta: dict, key: str = K_META) -> None:
     # Meta has no TTL — it's the heartbeat; staleness is judged from its ts.
-    await cache_set(K_META, meta, 0)
+    await cache_set(key, meta, 0)
 
 
 # ── reads (consumers) ───────────────────────────────────────────────────
@@ -75,8 +82,12 @@ async def get_host_drives() -> list:
     return await cache_get(K_HOST_DRIVES) or []
 
 
-async def get_meta() -> dict | None:
-    return await cache_get(K_META)
+async def get_host_sensors() -> dict | None:
+    return await cache_get(K_HOST_SENSORS)
+
+
+async def get_meta(key: str = K_META) -> dict | None:
+    return await cache_get(key)
 
 
 # ── locate-LED command queue ────────────────────────────────────────────
@@ -126,20 +137,20 @@ _REFRESH_LUA = (
 )
 
 
-async def acquire_lock(token: str, ttl: int = 30) -> bool:
-    """Atomically claim the poller lock (or re-own it). True if held."""
+async def acquire_lock(token: str, ttl: int = 30, key: str = K_LOCK) -> bool:
+    """Atomically claim a single-instance lock (or re-own it). True if held."""
     client = get_client()
     if client is None:
         return True  # no Redis → no coordination possible; run anyway
-    return bool(await client.eval(_ACQUIRE_LUA, 1, K_LOCK, token, ttl))
+    return bool(await client.eval(_ACQUIRE_LUA, 1, key, token, ttl))
 
 
-async def refresh_lock(token: str, ttl: int = 30) -> bool:
+async def refresh_lock(token: str, ttl: int = 30, key: str = K_LOCK) -> bool:
     """Atomically extend the lock iff we still own it."""
     client = get_client()
     if client is None:
         return True
-    return bool(await client.eval(_REFRESH_LUA, 1, K_LOCK, token, ttl))
+    return bool(await client.eval(_REFRESH_LUA, 1, key, token, ttl))
 
 
 def now() -> float: