thermal: van-thermal daemon (CPU+NVMe monitor, alert, log)

Single sysfs sample loop drives three jobs off one daemon (modeled on
van-failover):

- live state at /run/van-thermal/state.json; new Cockpit "Temperatures"
  card reads it in the existing 5s loop (no per-refresh `sensors` shell-out)
- journal alerts on ok<->warn<->crit crossings, with clear_margin hysteresis
- throttled, self-rotating CSV history at /var/log/van-thermal.csv

Sensors resolved by hwmon name+label (coretemp/Package id 0, nvme/Composite),
never by hwmonN index (not stable across boots). Defaults: CPU warn 80 /
crit 95, NVMe warn 65 / crit 70. deploy.sh installs + enables the service.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

power/thermal-config.json

@@ -0,0 +1,10 @@
+{
+  "sample_interval": 10,
+  "log_interval": 60,
+  "log_path": "/var/log/van-thermal.csv",
+  "log_max_bytes": 5242880,
+  "sensors": [
+    { "name": "cpu",  "hwmon": "coretemp", "label": "Package id 0", "warn": 80, "crit": 95, "clear_margin": 5 },
+    { "name": "nvme", "hwmon": "nvme",     "label": "Composite",    "warn": 65, "crit": 70, "clear_margin": 5 }
+  ]
+}