Purge remaining references to removed western apps

The quattro upgrade script no longer registers the HEY mailto
handler, installer tips stop naming LibreOffice, and the hotkeys,
GUIs, and web-apps manuals drop the entries for removed apps.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QKxGW1raAWaqeU8WdHsMsp

bin/omarchy-upgrade-to-quattro

@@ -2196,10 +2196,6 @@ fi
 if command -v xdg-settings >/dev/null 2>&1; then
   env -u BROWSER xdg-settings set default-web-browser chromium.desktop || true
 fi
-if command -v xdg-mime >/dev/null 2>&1; then
-  xdg-mime default HEY.desktop x-scheme-handler/mailto || true
-fi
-
 # This script is fetched from the branch and runs against whatever packaged
 # tree the channel currently serves, so the packaged tree can be older than the
 # script. The completion markers are written directly rather than through