Install ChatGPT as a desktop app under Install > AI (#6747)

Drops the ChatGPT web app from the default set at the same time, so installing
the openai-codex-desktop package can't leave two identical-looking ChatGPT
entries in the launcher. Super + Shift + A still opens the web version, which
is the only place it was really used.

The bundled ChatGPT icon stays: the package's own chatgpt.desktop asks for
Icon=chatgpt and ships no hicolor icon of its own.

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

bin/omarchy-install-ai-chatgpt

@@ -0,0 +1,15 @@
+#!/bin/bash
+
+# omarchy:summary=Install the ChatGPT desktop app
+# omarchy:requires-sudo=true
+
+set -e
+
+echo "Installing ChatGPT..."
+omarchy-pkg-add openai-codex-desktop
+
+echo "Opening ChatGPT..."
+setsid uwsm-app -- /usr/bin/chatgpt >/dev/null 2>&1 &
+
+echo ""
+echo "ChatGPT has been installed."