Switch from Dunst to Deadd Notifications

- Add Deadd Notification Center config & colors to README
- Add Deadd control script
- Exclude picom rounded corners for Deadd Notification
  Center since they are handled by the deadd config
- Replace dunst with deadd in startup script
- Pause/unpause deadd notifications in game launch/exit scripts
- Update control center script to use deadd

.scripts/game_launch.sh

@@ -1,3 +1,2 @@
 #!/bin/bash
-# /home/sravan/.scripts/picom.sh --off
-/home/sravan/.scripts/dunst.sh --dnd
+/home/sravan/.scripts/deadd.sh --pause