Turn the displays off while the headset isn't used, and keep it awake on a charger

A display mount that covers the proximity sensor makes the headset seem
worn, so SteamVR never turned its displays off and they stayed on all
night. The new power service, ft-powerd (frametop-power.service), goes by
use instead: after DISPLAY_OFF_MIN minutes in which the headset and
controllers didn't move and no input device was used, it turns the
backlight off, and the next movement or input turns it back on.

The new Power tab in Frametop Display Settings sets that time and has a
Stay awake while plugged in switch. The switch sets Steam's own "When
Plugged In and Idle -> Sleep after" to Never through Steam's UI, so the
Frame stays reachable remotely while the power button still works.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

session/frametop.conf.example

@@ -31,5 +31,8 @@ POINTER_GAZE_HOLD=0.5      # gaze mode: a press held this long (s) without movin
 POINTER_GAZE_SHOW=1        # gaze mode: the dot shows this long (s) after the mouse moves it; also while a press is held, and a pulse per click
 META_DASHBOARD=0   # 1 = a Meta tap on a pass-through keyboard toggles the SteamVR dashboard (pointer mode only)
 SHARE_KEYS=0       # 1 = keys of keyboards grabbed for the desktop also go to @frametop_keys, for hotkey tools (any local process can listen)
+DISPLAY_OFF_MIN=0  # minutes without use before frametop-power turns the displays off, even if the headset seems worn (0 = never)
+DISPLAY_MOVE_MM=5  # displays off: the headset or a controller moving this far (mm) within 10 s counts as use
+DISPLAY_MOVE_DEG=0.5 # displays off: or turning this far (degrees) within 10 s
 LAYOUT_GRAB_OFFSET=0.075   # arranging screens: where the floating window's grab bar is, in metres below the screen
 LAYOUT_SLIDE_SPEED=0.5     # arranging screens: how fast the invisible controller slides a grabbed screen (m/s)