Add missing macOS app icon sizes

AppIcon.appiconset only defined an iOS "universal" 1024x1024 entry, so
the macOS build had no mac-idiom icon at all — App Store Connect
rejected uploads for missing the required 512pt@2x (1024x1024) image.
Generates the full mac icon set (16/32/128/256/512pt at 1x/2x) from
the existing 1024px source and wires it into Contents.json.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FXcrACM5sok3M1KQJ8kByy

iosApp/iosApp.xcodeproj/project.pbxproj

@@ -11,7 +11,7 @@
 /* End PBXFileReference section */
 
 /* Begin PBXFileSystemSynchronizedBuildFileExceptionSet section */
-		D262C3356B38E7E13FFE64E4 /* Exceptions for "iosApp" folder in "iosApp" target */ = {
+		D262C3356B38E7E13FFE64E4 /* PBXFileSystemSynchronizedBuildFileExceptionSet */ = {
 			isa = PBXFileSystemSynchronizedBuildFileExceptionSet;
 			membershipExceptions = (
 				Info.plist,
@@ -23,13 +23,21 @@
 /* Begin PBXFileSystemSynchronizedRootGroup section */
 		24D66E9CCFCEB2D844328B79 /* Configuration */ = {
 			isa = PBXFileSystemSynchronizedRootGroup;
+			explicitFileTypes = {
+			};
+			explicitFolders = (
+			);
 			path = Configuration;
 			sourceTree = "<group>";
 		};
 		55D8B06C58654F251C5B3381 /* iosApp */ = {
 			isa = PBXFileSystemSynchronizedRootGroup;
 			exceptions = (
-				D262C3356B38E7E13FFE64E4 /* Exceptions for "iosApp" folder in "iosApp" target */,
+				D262C3356B38E7E13FFE64E4 /* PBXFileSystemSynchronizedBuildFileExceptionSet */,
+			);
+			explicitFileTypes = {
+			};
+			explicitFolders = (
 			);
 			path = iosApp;
 			sourceTree = "<group>";