Make status indicators event-driven instead of polling

The indicators widget broadcast a refresh every 2s, fanning out to four
status subprocesses (nightlight, idle, reminder, screen-recording), and
NightLight/StayAwake each ran an additional 5s poll. On an idle desktop
this was the dominant source of process churn (~33 of ~53 forks/sec in a
VM). The state-changing commands already push `omarchy.indicators
refresh` over IPC, so the polling was redundant.

Drop the 2s broadcast and the two 5s timers; indicators now refresh at
startup and on the IPC push. Also fix three callers that pushed to the
wrong target `Indicators` instead of `omarchy.indicators` (screen
recording, notification silencing, and the omarchy-shell help example) —
those pushes silently failed and only appeared to work because the poll
masked them.

Idle fork rate drops ~53/s to ~20/s.

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

bin/omarchy-capture-screenrecording

@@ -222,7 +222,7 @@ stop_screenrecording() {
 }
 
 toggle_screenrecording_indicator() {
-  omarchy-shell -q Indicators refresh
+  omarchy-shell -q omarchy.indicators refresh
 }
 
 screenrecording_active() {