Use NSApplication.applicationIconImage for app icon

In GetPoeditAppIcon(), use the macOS native API for obtaining
application icon instead of relying on knowing what the asset's name is.

Unlike the old code, this works with macOS 26's new icon format.

Author: vslavik

Poedit.xcodeproj/project.pbxproj

@@ -463,7 +463,7 @@
 		B26D064E182506E40069C378 /* languagectrl.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = languagectrl.h; sourceTree = "<group>"; };
 		B26D0653182697200069C378 /* welcomescreen.cpp */ = {isa = PBXFileReference; explicitFileType = sourcecode.cpp.objcpp; fileEncoding = 4; path = welcomescreen.cpp; sourceTree = "<group>"; };
 		B26D0654182697200069C378 /* welcomescreen.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = welcomescreen.h; sourceTree = "<group>"; };
-		B26E2C8125A244FE008D6DF1 /* icons.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = icons.cpp; sourceTree = "<group>"; };
+		B26E2C8125A244FE008D6DF1 /* icons.cpp */ = {isa = PBXFileReference; explicitFileType = sourcecode.cpp.objcpp; fileEncoding = 4; path = icons.cpp; sourceTree = "<group>"; };
 		B26E2C8225A244FF008D6DF1 /* icons.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = icons.h; sourceTree = "<group>"; };
 		B26E2C8425A24541008D6DF1 /* menus.cpp */ = {isa = PBXFileReference; explicitFileType = sourcecode.cpp.objcpp; fileEncoding = 4; path = menus.cpp; sourceTree = "<group>"; };
 		B26E2C8525A24541008D6DF1 /* menus.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = menus.h; sourceTree = "<group>"; };

src/icons.cpp

@@ -291,6 +291,8 @@ wxBitmap GetPoeditAppIcon([[maybe_unused]]int pointSize)
         appicon.SetScaleFactor(scale);
         return appicon;
     }
+#elif defined(__WXOSX__)
+    return wxBitmap(NSApplication.sharedApplication.applicationIconImage);
 #elif defined(__WXGTK__)
     return wxArtProvider::GetIcon("net.poedit.Poedit", wxART_FRAME_ICON, wxSize(pointSize, pointSize));
 #else