Add per-enclosure temperature metrics + Home Assistant MQTT publisher

- enclosure: fetch SES element descriptor page (0x07) and label temp/fan/
  psu/voltage elements with human-readable names
- temps service + /api/temps: per-enclosure hotspot (max across SES sensors
  and housed drive temps) plus named SES sensor list
- mqtt_publisher: paho-mqtt with HA discovery (device per enclosure, hotspot
  + per-sensor entities), LWT availability, opt-in via MQTT_HOST
- secrets: OpenBao KV v2 reader; MQTT creds sourced from secret/home_assistant
  with env fallback
- compose/requirements/README updated

models/schemas.py

@@ -67,6 +67,7 @@ class SlotWithDrive(BaseModel):
 
 class PsuStatus(BaseModel):
     index: int
+    name: str | None = None
     status: str
     fail: bool = False
     ac_fail: bool = False
@@ -75,6 +76,7 @@ class PsuStatus(BaseModel):
 
 class FanStatus(BaseModel):
     index: int
+    name: str | None = None
     status: str
     rpm: int | None = None
     fail: bool = False
@@ -82,12 +84,14 @@ class FanStatus(BaseModel):
 
 class TempSensor(BaseModel):
     index: int
+    name: str | None = None
     status: str
     temperature_c: float | None = None
 
 
 class VoltageSensor(BaseModel):
     index: int
+    name: str | None = None
     status: str
     voltage: float | None = None
 
@@ -147,3 +151,25 @@ class Overview(BaseModel):
 class HealthCheck(BaseModel):
     status: str
     tools: dict[str, bool]
+
+
+class EnclosureTempSensor(BaseModel):
+    index: int
+    name: str | None = None
+    status: str
+    temperature_c: float | None = None
+
+
+class EnclosureTemps(BaseModel):
+    id: str
+    vendor: str
+    model: str
+    hotspot_c: float | None = None
+    drive_max_c: float | None = None
+    drive_temp_count: int = 0
+    sensors: list[EnclosureTempSensor] = []
+
+
+class TempSnapshot(BaseModel):
+    node: str
+    enclosures: list[EnclosureTemps] = []