fix(plant): alert hygiene — watchdog gate, trend smoothing, UPS [#344]

Three live-fire defects: unconditional 30-min watchdog page, tsys6 flap
false-positive, Tripp Lite runtime-low gap. TDD: 4 new regression tests.
On-box ha core check passed before commit.

Meat + verification: https://projects.knownelement.com/issues/344#note-4966

packages/doorman.yaml

@@ -84,11 +84,14 @@ input_boolean:
 
 shell_command:
   # Unlock dispatch via curl — swapped from rest_command 2026-09-04: the
-  # rest_command integration silently fails to register on this box
-  # (404 on /api/services/rest_command despite valid config + secret;
-  # root-cause pending in #345/#741). curl is present in the HA core
-  # container. Token lives in the URL secret — process-list exposure
-  # accepted (isolated container).
+  # rest_command integration silently failed to register on this box
+  # (404 on /api/services/rest_command despite valid config + secret).
+  # NOT reproducible: 2026-09-06 the integration + doorman_unlock service
+  # are registered again (suspect: transient state after a reload-only
+  # deploy window; rest_command now also exposes a reload service).
+  # curl stays as the verified-live dispatch path — swapping back to
+  # rest_command (drops the token from the process list) is gated on one
+  # armed badge re-test (founder call, questions-v1).
   doorman_unlock: "curl -sS -m 10 '{{ doorman_unlock_url }}'"
 
 rest_command: