Spawn shell subprocesses with bash -c instead of bash -lc

Each `bash -lc` starts a login shell that re-sources the profile
(mise activation, /etc/profile.d) on every invocation — ~16 forks per
call versus ~2 for `bash -c` — which taxes every menu/panel/launcher
action the shell shells out for. The session already exports PATH and
env to the shell, so omarchy commands resolve fine under `bash -c`.

Switch the internal/omarchy-owned spawns (theme+background switches,
brightness, monitor scaling, DNS, lock/fingerprint, keyboard-layout
probe, voxtype status, and the `:`/printf state-file writes) to
`bash -c`. Leave `bash -lc` on the sites that run user-configurable
commands (custom bar-widget exec, menu provider/guard scripts,
launcher scan commands, configurable idle/screensaver command), where
a user's command may rely on their login environment.

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

shell/plugins/services/idle/Service.qml

@@ -300,7 +300,7 @@ Item {
 
   Process {
     id: stayAwakeStateProbe
-    command: ["bash", "-lc", "mkdir -p \"$HOME/.local/state/omarchy/indicators\"; if [[ -f $HOME/.local/state/omarchy/indicators/stay-awake ]]; then echo yes; else echo no; fi"]
+    command: ["bash", "-c", "mkdir -p \"$HOME/.local/state/omarchy/indicators\"; if [[ -f $HOME/.local/state/omarchy/indicators/stay-awake ]]; then echo yes; else echo no; fi"]
     stdout: SplitParser {
       onRead: function(line) { root.applyStayAwake(String(line).trim() === "yes", false, "state-file") }
     }