host_sensors: read extra hwmon chips (dell_smm) as env sensors

Boxes without IPMI (Dell workstations like dev-linux) expose CPU/ambient/
SODIMM/board temps via the BIOS SMM interface (dell_smm hwmon). Add
read_hwmon_env(): labelled temps from chips in HOST_HWMON_CHIPS (default
'dell_smm') as env sensors, named '<chip> <label>' with index suffix for
repeated labels. Merged into the host-poller env sweep. No-op on hosts without
the configured chips.

host_poller.py

@@ -22,7 +22,7 @@ import time
 from services import store
 from services.cache import close_cache, init_cache, redis_available
 from services.host import get_host_drives
-from services.host_sensors import read_coretemp, read_ipmi_temps
+from services.host_sensors import read_coretemp, read_hwmon_env, read_ipmi_temps
 
 logging.basicConfig(
     level=logging.INFO,
@@ -47,7 +47,7 @@ async def sweep_env() -> None:
     except Exception as e:
         errors.append(f"ipmi:{e}")
         ipmi = []
-    env = [s for s in ipmi if s.get("kind") == "env"]
+    env = [s for s in ipmi if s.get("kind") == "env"] + read_hwmon_env()
     cpu = read_coretemp() or [s for s in ipmi if s.get("kind") == "cpu"]
 
     await store.set_host_sensors({