fix: macOS deep links after wxWidgets 3.3.2 upgrade (#13737)

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>

src/slic3r/GUI/DeepLinkHandlerMac.mm

@@ -0,0 +1,41 @@
+#import <AppKit/AppKit.h>
+#import <Foundation/Foundation.h>
+
+#include <boost/log/trivial.hpp>
+
+#include "DeepLinkHandlerMac.h"
+#include "GUI_App.hpp"
+
+@interface OrcaDeepLinkHandler : NSObject
+- (void)handleGetURLEvent:(NSAppleEventDescriptor *)event withReplyEvent:(NSAppleEventDescriptor *)reply;
+@end
+
+@implementation OrcaDeepLinkHandler
+- (void)handleGetURLEvent:(NSAppleEventDescriptor *)event withReplyEvent:(NSAppleEventDescriptor *)reply
+{
+    NSString *url = [[event paramDescriptorForKeyword:keyDirectObject] stringValue];
+    if (url == nil || url.length == 0)
+        return;
+    BOOST_LOG_TRIVIAL(info) << "Deep link received: " << [url UTF8String];
+    Slic3r::GUI::wxGetApp().MacOpenURL(wxString::FromUTF8([url UTF8String]));
+}
+@end
+
+namespace Slic3r {
+namespace GUI {
+
+void register_mac_deep_link_handler()
+{
+    static OrcaDeepLinkHandler *handler = nil;
+    if (handler == nil)
+        handler = [[OrcaDeepLinkHandler alloc] init];
+
+    [[NSAppleEventManager sharedAppleEventManager]
+        setEventHandler:handler
+            andSelector:@selector(handleGetURLEvent:withReplyEvent:)
+          forEventClass:kInternetEventClass
+             andEventID:kAEGetURL];
+}
+
+} // namespace GUI
+} // namespace Slic3r