Stop the dashboard polling harder than its data can change

Every poll after the first asked for ?live=1, so the page paid a full collection — partner SSH
timeouts included — every two seconds while the tmpfs cache it was built around went unused.
Polls are now guarded against overlap and stop while the tab is hidden, repeated failures say so
instead of leaving the last good reading on screen, and two functions nothing called are gone.

Plugin/unraid/api/system.php

@@ -5,6 +5,13 @@
 //   most destructive operations the plugin can perform, deliberately isolated in one small
 //   file rather than folded into a general-purpose action endpoint.
 //
+// STATUS
+//   No UI caller. pages/monitor.php held the only one — a vvArrayAction() that no button on any
+//   tab invoked — and it was removed 2026-08-07 rather than left as an unreachable handler for
+//   these three commands. The endpoint is kept because it is complete and correct, and because
+//   power control is a thing this plugin will plausibly want; wiring it up is adding buttons, not
+//   writing an endpoint. Anything added here must keep the guarantees below intact.
+//
 // OPERATIONAL MODEL
 //   The command is detached and the response returns immediately. A shutdown kills the web
 //   server that is serving this request, so waiting on the child would mean the browser sees