Refactor codebase to use nix modules

programs/eww/config/modules/powerbar.yuck

@@ -1,15 +0,0 @@
-(defwidget powerbar []
-  (box
-      :orientation "vertical"
-      :spacing 8
-      :space-evenly false
-      :style "color: #FAB387"
-    (progress
-        :orientation "v"
-        :value {100 - power})
-    "電"
-  )
-)
-
-(defpoll power :interval "1m"
-  "cat /sys/class/power_supply/BAT1/capacity")