fix: resolve Windows build error and macOS JavaScript execution

WINDOWS FIX:
- Fixed compilation error in UwbWebView.cs line 143
- UniTask.WhenAny returns a tuple (int winIndex, T result), not just int
- Corrected to use tuple deconstruction: var (winIndex, _) = await UniTask.WhenAny(...)

MACOS FIX:
- WKWebView requires being in view hierarchy to execute JavaScript
- Set webView.hidden = NO and positioned offscreen (-10000, -10000)
- Added WebView to main window's content view
- This allows JavaScript (game-bridge) to execute and send callbacks

Both fixes address the 'App stuck in Initialisation' issue by ensuring
JavaScript can execute and callbacks can reach Unity on both platforms.

Author: rodrigo-fournier-immutable

src/Packages/Passport/Runtime/Scripts/Private/Uwb/UwbWebView.cs

@@ -138,9 +138,9 @@ private async UniTask WaitForClientConnected(WebBrowserClient webBrowserClient)
             Debug.Log($"[UwbWebView] Waiting up to {timeoutSeconds} seconds for OnLoadFinish event...");
 
             // Race between completion and timeout
-            var completedTask = await UniTask.WhenAny(completionTask, timeoutTask);
+            var (winIndex, _) = await UniTask.WhenAny(completionTask, timeoutTask);
 
-            if (completedTask == 1) // Timeout won
+            if (winIndex == 1) // Timeout won
             {
                 webBrowserClient.OnLoadFinish -= OnLoadFinish;
                 var errorMsg = $"[UwbWebView] Timeout after {timeoutSeconds} seconds waiting for browser OnLoadFinish event. " +