thermal+ha: don't lose boot-time pages; stop HA gracefully

van-thermal fires its first sample seconds after start, and the Pi often
boots hot — order after network-online.target and retry network failures
in the Pushover send path (3 attempts, 15s apart) so that page survives
DNS not being up yet. Non-200 responses still don't retry.

The Quadlet gets StopTimeout=120: podman's default 10s window SIGKILLed
HA mid-flush and the recorder complained about an unclean sqlite shutdown
on every start. Verified clean after a full stop/start cycle.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ha/homeassistant.container

@@ -24,6 +24,9 @@ Environment=TZ=America/Toronto
 # recovery. HA is rootful + host-net anyway.
 PodmanArgs=--security-opt apparmor=unconfined
 AddCapability=NET_ADMIN NET_RAW
+# Podman's default 10s stop window SIGKILLs HA mid-flush and the recorder
+# complains about an unclean sqlite shutdown on the next start.
+StopTimeout=120
 
 [Service]
 Restart=always