Re-add cava (music visualiser)

system/home/shell/cava.nix

@@ -0,0 +1,18 @@
+{ config, ... }:
+{
+  programs.cava = {
+    enable = true;
+    settings = {
+      color = with config.lib.stylix.colors.withHashtag; {
+        gradient = 1;
+        gradient_count = 6;
+        gradient_color_1 = "'${red}'";
+        gradient_color_2 = "'${yellow}'";
+        gradient_color_3 = "'${green}'";
+        gradient_color_4 = "'${cyan}'";
+        gradient_color_5 = "'${blue}'";
+        gradient_color_6 = "'${magenta}'";
+      };
+    };
+  };
+}

system/home/shell/default.nix

@@ -9,6 +9,7 @@
     ./git.nix
     ./ssh.nix
     ./starship.nix
+    ./cava.nix
   ];
   home = {
     packages = with pkgs; [