Split into dedicated hardware poller + read-only consumers

Rearchitect so a single poller process is the sole owner of all SAS/SMART/
SES hardware I/O, serialized behind one gate and paced, writing results to
Redis. The API/web and MQTT publisher become pure Redis readers — they no
longer issue any subprocess and can restart freely without touching the bus.

This addresses backplane/expander stress from concurrent + restart-triggered
SMART/SES storms (the prior model re-ran a hardware sweep on every container
start, and polled sg_ses 0x02+0x07 every 60s; 0x07 errored on the IOM6/
Xyratex expanders).

- poller.py: paced sweep (inventory, SMART per-drive w/ gap, SES 0x02, ZFS,
  host/MegaRAID), startup jitter, single-instance Redis lock, LED-queue worker
- services/hwgate.py: global serialization semaphore (POLL_CONCURRENCY=1)
- services/store.py: Redis as the only producer<->consumer interface + LED queue
- services/health.py: shared drive-health classifier (fixes overview double-count)
- gate smartctl/sg_ses/zpool/ledctl; drop sg_ses 0x07 from the hot path
- routers + temps read-only from the store; main.py drops the in-process poller
- compose: 3 services (privileged poller + unprivileged app + redis) w/ pacing knobs

services/temps.py

@@ -1,74 +1,57 @@
-"""Per-enclosure temperature aggregation.
+"""Per-enclosure temperature aggregation (read-only consumer).
 
-Builds a compact snapshot of enclosure temperatures suitable for Home
-Assistant: each named SES temperature sensor plus a derived per-enclosure
-hotspot (the hottest reading across SES sensors *and* the drives housed in
-that enclosure — drive temps are usually the real hotspot signal).
+Reads the poller's data out of Redis — never touches hardware. Each named
+SES temperature sensor plus a derived per-enclosure hotspot (the hottest
+reading across SES sensors *and* the drives housed in that enclosure —
+drive temps are usually the real hotspot signal).
 """
-import asyncio
 import logging
+import os
 import socket
 
-from services.enclosure import discover_enclosures, get_enclosure_status, list_slots
-from services.smart import get_smart_data
+from services import store
 
 logger = logging.getLogger(__name__)
 
 
 def get_node_id() -> str:
     """Stable identifier for this monitor instance (defaults to hostname)."""
-    import os
-
     return os.environ.get("MQTT_NODE_ID") or socket.gethostname() or "jbod-monitor"
 
 
 async def build_temp_snapshot() -> dict:
-    """Collect per-enclosure temperature metrics for all enclosures."""
-    enclosures = discover_enclosures()
-
-    async def _health(enc):
-        if enc.get("sg_device"):
-            return await get_enclosure_status(enc["sg_device"])
-        return None
-
-    health_results = await asyncio.gather(
-        *[_health(enc) for enc in enclosures], return_exceptions=True
-    )
-
+    """Collect per-enclosure temperature metrics from the store."""
+    inventory = await store.get_inventory()
     out_enclosures: list[dict] = []
-    for enc, health in zip(enclosures, health_results):
-        if isinstance(health, Exception):
-            logger.warning("SES health failed for %s: %s", enc["id"], health)
-            health = None
+
+    for enc in inventory.get("enclosures", []):
+        ses = await store.get_ses(enc["id"]) or {}
 
         sensors: list[dict] = []
         sensor_temps: list[float] = []
-        if isinstance(health, dict):
-            for t in health.get("temps", []):
-                temp = t.get("temperature_c")
-                sensors.append({
-                    "index": t["index"],
-                    "name": t.get("name"),
-                    "status": t.get("status", "Unknown"),
-                    "temperature_c": temp,
-                })
-                if isinstance(temp, (int, float)) and temp > 0:
-                    sensor_temps.append(float(temp))
+        for t in ses.get("temps", []):
+            temp = t.get("temperature_c")
+            sensors.append({
+                "index": t["index"],
+                "name": t.get("name"),
+                "status": t.get("status", "Unknown"),
+                "temperature_c": temp,
+            })
+            if isinstance(temp, (int, float)) and temp > 0:
+                sensor_temps.append(float(temp))
 
         # Drive temperatures for drives housed in this enclosure.
         drive_temps: list[float] = []
-        devices = [s["device"] for s in list_slots(enc["id"]) if s.get("device")]
-        if devices:
-            smart_results = await asyncio.gather(
-                *[get_smart_data(d) for d in devices], return_exceptions=True
-            )
-            for res in smart_results:
-                if isinstance(res, Exception):
-                    continue
-                data, _hit = res
-                temp = data.get("temperature_c")
-                if isinstance(temp, (int, float)) and temp > 0:
-                    drive_temps.append(float(temp))
+        for slot in enc.get("slots", []):
+            dev = slot.get("device")
+            if not dev:
+                continue
+            sm = await store.get_smart(dev)
+            if not sm:
+                continue
+            temp = sm.get("temperature_c")
+            if isinstance(temp, (int, float)) and temp > 0:
+                drive_temps.append(float(temp))
 
         all_temps = sensor_temps + drive_temps
         out_enclosures.append({