feat: add laptop/display brightness modulation

scripts/copy_icons.sh

@@ -153,6 +153,7 @@ ICONS=(
     "apps/scalable/bluetooth.svg"
     "panel/volume-level-high.svg"
     "status/symbolic/audio-volume-high-symbolic.svg"
+    "status/symbolic/display-brightness-symbolic.svg"
     "apps/scalable/gnome-logout.svg"
     "apps/scalable/lock.svg"
     # Consent prompt, one per capability (see montauk/consent.h). The clock,