feat(fish): disable fish greeting by default

- Added `set fish_greeting` to disable the default greeting in interactive shell initialization.
- Simplifies the shell startup experience for users.

modules/home/cli-apps/fish/default.nix

@@ -18,6 +18,7 @@ in
     programs.fish = {
       enable = true;
       interactiveShellInit = ''
+        set fish_greeting # Disable greeting
         function msh --wraps mosh --description 'mosh with tmux'
           if not set -q argv[1]
             echo 'Usage: msh [user@]host [command]'