macos: add a variety of artist-drawn alternate icons

This is just a fun change to add a bunch of alternate icons. We don't
want to add too many since this increases the final bundle size but we
also want to have some fun. :)

src/config/Config.zig

@@ -1972,6 +1972,9 @@ keybind: Keybinds = .{},
 /// Valid values:
 ///
 ///  * `official` - Use the official Ghostty icon.
+///  * `blueprint`, `chalkboard`, `microchip`, `glass`, `holographic`,
+///    `paper`, `retro`, `xray` - Official variants of the Ghostty icon
+///    hand-created by artists (no AI).
 ///  * `custom-style` - Use the official Ghostty icon but with custom
 ///    styles applied to various layers. The custom styles must be
 ///    specified using the additional `macos-icon`-prefixed configurations.
@@ -5719,6 +5722,14 @@ pub const MacTitlebarProxyIcon = enum {
 /// format at all.
 pub const MacAppIcon = enum {
     official,
+    blueprint,
+    chalkboard,
+    microchip,
+    glass,
+    holographic,
+    paper,
+    retro,
+    xray,
     @"custom-style",
 };