* Migrate existing waybar configs to pin battery to BAT0
Follow-up to #4918: that PR updated the default template, but
existing users keep their copy at ~/.config/waybar/config.jsonc
and won't pick up the fix without running omarchy-refresh-waybar
(which wipes local customizations). Patch the existing file in
place and restart waybar.
* Make battery-pin migration tolerant of whitespace variants
Per Copilot review: grep/sed patterns now match "battery" : {,
"battery":{, and "bat" : "..." variants that hand-edited configs
may use. Also only restart waybar when a battery block actually
exists to edit.
