fix: show bluetooth icon instead of status text in Waybar

The bluetooth module displayed " {status}" (icon + text like
"on"/"off") which was inconsistent with other icon-only modules.

defaults/xdg/waybar/config

@@ -316,7 +316,7 @@
     },
     "bluetooth": {
         // "controller": "controller1", // specify the alias of the controller if there are more than 1 on the system
-        "format": " {status}",
+        "format": "󰂯",
         "format-disabled": "󰂲", // an empty format will hide the module
         "format-connected": "<small>{num_connections}</small>",
         "tooltip-format": "{controller_alias}\t{controller_address}",