Desktop: add tailscale system tray

roles/desktop/services/tailscale.nix

@@ -0,0 +1,16 @@
+{pkgs, ...}: {
+  home-manager.users.toast = {
+    services.tailscale-systray = {
+      enable = true;
+      package = pkgs.tailscale.overrideAttrs {
+        postPatch = ''
+          substituteInPlace client/systray/logo.go --replace-fail \
+            "color.NRGBA{0, 0, 0, 255}" "color.NRGBA{0, 0, 0, 0}"
+        '';
+        # Only use this for the tray, so no testing is needed
+        # Makes the build last a lot less too
+        doCheck = false;
+      };
+    };
+  };
+}