Add openai-codex-desktop

Official ChatGPT/Codex desktop app, now shipping native Linux debs from
OpenAI. Fast ring, so it lands in stable alongside edge.

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

pkgbuilds/openai-codex-desktop/.omarchy/package.json

@@ -0,0 +1,5 @@
+{
+  "source": "aur",
+  "release_ring": "fast",
+  "upstream_commit": "05f12e3c51ce07efb996698d4fae94327f45f03b"
+}