feat(t3_code): add T3 Code AppImage launcher and desktop entry

users/richie/home/gui/t3_code/default.nix

@@ -0,0 +1,36 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  t3-code = pkgs.writeShellApplication {
+    name = "t3-code";
+    runtimeInputs = with pkgs; [
+      coreutils
+      kdePackages.kdialog
+    ];
+    text = builtins.readFile ./launch.sh;
+  };
+in
+{
+  home = {
+    # AppImages are runnable from a shell as well
+    sessionPath = [ "${config.home.homeDirectory}/app_images" ];
+    packages = [ t3-code ];
+  };
+
+  # KDE builds its menu from desktop entries, not from PATH
+  xdg.desktopEntries.t3-code = {
+    name = "T3 Code";
+    genericName = "Code Editor";
+    comment = "Newest T3 Code AppImage in ~/app_images";
+    exec = "${lib.getExe t3-code} %U";
+    icon = "${./icon.png}";
+    terminal = false;
+    categories = [ "Development" ];
+    startupNotify = true;
+    settings.StartupWMClass = "t3code";
+  };
+}