feat: add brightness keybinds and notification

pkgs/scripts/brightness.nix

@@ -0,0 +1,30 @@
+{
+  writeShellApplication,
+  bc,
+  libnotify,
+  brightnessctl,
+}:
+writeShellApplication {
+  name = "brightness";
+  text = ''
+    set -euo pipefail
+
+    ${brightnessctl}/bin/brightnessctl "$1" "$2"
+    case "$2" in
+      "+"*) image=${./assets}/brightness-increase.svg ;;
+      *"-") image=${./assets}/brightness-decrease.svg ;;
+    esac
+
+    max=$(${brightnessctl}/bin/brightnessctl -m max)
+    value=$(${brightnessctl}/bin/brightnessctl -m get)
+    value=$(${bc}/bin/bc <<< "scale=0; 100*$value/$max")
+    ${libnotify}/bin/notify-send \
+      "Brightness" \
+      --hint=string:image-path:"$image" \
+      --hint=int:value:"$value" \
+      --hint="string:wired-tag:indicator" \
+      --hint="string:wired-note:brightness" \
+      --expire-time=1000 \
+      || true
+  '';
+}