Fix macOS orcaslicer:// deep links after wxWidgets 3.3.2 upgrade
Install an OrcaSlicer-owned kAEGetURL Apple Event handler from
on_init_inner(). The wxWidgets 3.3.2 handler registered in
applicationWillFinishLaunching: stopped delivering URL events to
GUI_App::MacOpenURL on macOS (#13119), so links from Printables /
Thingiverse opened a blank project instead of importing the model.
Registering our own handler late in startup is last-writer-wins on
NSAppleEventManager and routes back to the existing MacOpenURL ->
start_download path, restoring the pre-upgrade behavior without
touching wxWidgets.
Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
