nixos: add quickshell/waybar/taffybar modules

- Switch taffybar input to the local submodule
- Add caelestia quickshell (home-manager module)
- Make waybar/taffybar mutually exclusive, defaulting based on xmonad
- Move tray ordering and status notifier watcher config into the right modules

nixos/machines/strixi-minaj.nix

@@ -17,6 +17,7 @@
   myModules.gitea-runner.enable = false;
   myModules.nvidia.enable = true;
   myModules.electron.enable = true;
+  myModules.quickshell.enable = true;
   myModules.wyoming.enable = false;
   myModules.tts.enable = false;