Adds a "Mirror Display" entry that calls a helper script which finds
the first connected non-internal monitor and toggles mirroring of
eDP-1 onto it via hyprctl. Use case: plugging into a conference room
TV/projector while travelling.
Also fixes the menu's "Screenshot full" entry to capture the active
output instead of the hardcoded DP-1, matching the equivalent fix to
the Ctrl+Print keybind.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
