Feature: Add spotify module.

- librespot as systemd service for backend.
  - Spotify-qt for qt-based GUI.
  - ncspot for TUI.

dotfiles/modules/programs/spotify.nix

@@ -0,0 +1,22 @@
+{ pkgs, sys, ... }: {
+  networking.firewall.allowedTCPPorts = [ 57621 ];
+  networking.firewall.allowedUDPPorts = [ 5353 ];
+  home-manager.users.${sys.username} = {
+    home.packages = with pkgs; [
+      spotify-qt
+      ncspot
+      librespot
+    ];
+    systemd.user.services.librespot = {
+      Unit = {
+        Description = "Librespot (an open source Spotify client)";
+        Documentation = [ "https://github.com/librespot-org/librespot" "https://github.com/librespot-org/librespot/wiki/Options" ];
+      };
+      Service = {
+        Restart = "always";
+        RestartSec = 10;
+        ExecStart = "${pkgs.librespot}/bin/librespot --backend pulseaudio --system-cache /home/${sys.username}/.spotify -j";
+      };
+    };
+  };
+}