Open the keybindings menu on first login

The welcome toast spent three lines telling you about a cheatsheet that takes
one keystroke to read, and the only way to act on it was to click the toast,
which opened that cheatsheet. Open it directly instead.

Dismissing the menu exits non-zero, since no selection was made, so the step
tolerates that rather than failing first run and retrying the whole sequence
next login.

It also goes last now. The menu blocks until it is answered, and the Wi-Fi and
update toasts are the only other things left to show, so sending those first
leaves them waiting underneath rather than behind an open menu.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

install/user/first-run/keybindings.sh

@@ -0,0 +1,4 @@
+# Greet the first login with the cheatsheet itself rather than a toast
+# pointing at it. The menu blocks until it is answered, and dismissing it
+# exits non-zero, which is a normal way to close it.
+omarchy-menu-keybindings || true

install/user/first-run/welcome.sh

@@ -1,3 +0,0 @@
-omarchy-notification-send -u critical -g  "Learn Keybindings" \
-  "Super + K for cheatsheet.\nSuper + Space for application launcher.\nSuper + Alt + Space for Omarchy Menu." \
-  --exec omarchy-menu-keybindings