Add WPCom connection setup ViewModel logic and handler protocol

- Create WPComConnectionSetupHandlerProtocol with delegate pattern for
  handler-to-viewmodel communication
- Add stub WPComConnectionSetupHandler implementation (full implementation
  in follow-up PR)
- Update WPComConnectionSetupViewModel with SetupState, button handling,
  and delegate conformance
- Wire coordinator to use the new ViewModel signature
- Add @mainactor annotations where needed for thread safety
- Add MockWPComConnectionSetupHandler for testing
- Add 9 unit tests for ViewModel behavior

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: adborbas

WooCommerce/WooCommerce.xcodeproj/project.pbxproj

@@ -5661,7 +5661,6 @@
 /* Begin PBXFileSystemSynchronizedRootGroup section */
 		2D33E6B02DD1453E000C7198 /* WooShippingPaymentMethod */ = {isa = PBXFileSystemSynchronizedRootGroup; explicitFileTypes = {}; explicitFolders = (); path = WooShippingPaymentMethod; sourceTree = "<group>"; };
 		3F065E5C2F29B41D00881B6E /* Woo Watch App */ = {isa = PBXFileSystemSynchronizedRootGroup; exceptions = (3F065E742F29B41D00881B6E /* PBXFileSystemSynchronizedBuildFileExceptionSet */, ); explicitFileTypes = {}; explicitFolders = (); path = "Woo Watch App"; sourceTree = "<group>"; };
-		3F09040E2D26A40800D8ACCE /* WordPressAuthenticatorTests */ = {isa = PBXFileSystemSynchronizedRootGroup; exceptions = (3FD28D5E2D271391002EBB3D /* PBXFileSystemSynchronizedBuildFileExceptionSet */, ); explicitFileTypes = {}; explicitFolders = (); path = WordPressAuthenticatorTests; sourceTree = "<group>"; };
 		3F985FAD2F29AFD400924231 /* WatchWidgetsExtension */ = {isa = PBXFileSystemSynchronizedRootGroup; exceptions = (3F985FB12F29AFD400924231 /* PBXFileSystemSynchronizedBuildFileExceptionSet */, ); explicitFileTypes = {}; explicitFolders = (); path = WatchWidgetsExtension; sourceTree = "<group>"; };
 		3F985FBB2F29B00D00924231 /* NotificationExtension */ = {isa = PBXFileSystemSynchronizedRootGroup; exceptions = (3F985FC72F29B00D00924231 /* PBXFileSystemSynchronizedBuildFileExceptionSet */, 3F985FC82F29B00D00924231 /* PBXFileSystemSynchronizedBuildFileExceptionSet */, 3F985FC92F29B00D00924231 /* PBXFileSystemSynchronizedBuildFileExceptionSet */, ); explicitFileTypes = {}; explicitFolders = (); path = NotificationExtension; sourceTree = "<group>"; };
 		3F985FE02F29B06300924231 /* StoreWidgets */ = {isa = PBXFileSystemSynchronizedRootGroup; exceptions = (3F985FFC2F29B06300924231 /* PBXFileSystemSynchronizedBuildFileExceptionSet */, 3F985FFD2F29B06300924231 /* PBXFileSystemSynchronizedBuildFileExceptionSet */, 3F985FFE2F29B06300924231 /* PBXFileSystemSynchronizedBuildFileExceptionSet */, 3F985FFF2F29B06300924231 /* PBXFileSystemSynchronizedBuildFileExceptionSet */, ); explicitFileTypes = {}; explicitFolders = (Entitlements, ); path = StoreWidgets; sourceTree = "<group>"; };
@@ -5675,9 +5674,11 @@
 		DEDB5D342E7A68950022E5A1 /* Bookings */ = {isa = PBXFileSystemSynchronizedRootGroup; explicitFileTypes = {}; explicitFolders = (); path = Bookings; sourceTree = "<group>"; };
 		2D33E6B02DD1453E000C7198 /* WooShippingPaymentMethod */ = {
 			isa = PBXFileSystemSynchronizedRootGroup;
+		2D33E6B02DD1453E000C7198 /* WooShippingPaymentMethod */ = {
+			isa = PBXFileSystemSynchronizedRootGroup;
+			);
 			explicitFileTypes = {
 			};
-			explicitFolders = (
 			);
 			path = WooShippingPaymentMethod;
 			sourceTree = "<group>";
@@ -16051,10 +16052,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
-		CCDC49C623FFFFF4003166BA /* Sources */ = {
 			isa = PBXSourcesBuildPhase;
-			buildActionMask = 2147483647;
-			files = (
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};