Make BlazorWebView file-provider wrapping opt-in via AppType

The net11.0 base added UsePlatformHandler / IBlazorWebViewHandler and a test
(BlazorWebViewUsesCustomHandlerOperations) that asserts CreateFileProvider
returns the handler's own file provider by identity. The fingerprinting work
wrapped the platform provider whenever a bundled asset manifest was present -
even with no AppType - which broke that identity for every app with static
web assets.

Bind the whole feature (host-page rendering + @assets fingerprinting) to
AppType: when AppType is null, return the platform provider unchanged, exactly
preserving legacy behaviour. Fingerprinting only needs the wrapper on the
AppType path, which is where the manifest's ResourceAssetCollection is injected
into the renderer.

MacCatalyst device tests: 45 passed, 1 pre-existing skip - including the base's
custom-handler tests and the AppType/fingerprint tests together.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 2ca68fe1-bef6-46a6-a0fd-17b7654cef34

Author: mattleibow

src/BlazorWebView/src/Maui/BlazorWebView.cs

@@ -165,28 +165,25 @@ public virtual IFileProvider CreateFileProvider(string contentRootDir)
 			// Call into the platform-specific code to get that platform's asset file provider
 			var platformFileProvider = GetBlazorWebViewHandler().CreateFileProvider(contentRootDir);
 
+			// Everything below is opt-in via AppType. For the legacy HostPage (index.html) path, return
+			// the platform provider unchanged so existing behaviour - including the handler's own file
+			// provider instance - is preserved exactly.
+			if (AppType is null)
+			{
+				return platformFileProvider;
+			}
+
 			// Load the bundled static web assets manifest (if present) so that @Assets fingerprinting
 			// and fingerprinted-route serving work. The manifest lives outside the web root and is read
 			// from the app package, so it is never served to the web view. Absent (or on platforms
-			// without app-package access), fingerprinting simply stays off and behaviour is unchanged.
+			// without app-package access), fingerprinting simply stays off.
 			var manifest = StaticWebAssetsManifest.TryLoad();
 
-			string? hostPageRelativePath = null;
-			if (AppType is not null)
-			{
-				// When AppType is set, render the host document once. This also collects any interactive
-				// components declared with a render mode and registers them so they attach to the live
-				// document, and resolves @Assets using the manifest.
-				EnsureAppTypeRendered(manifest?.Assets);
-				hostPageRelativePath = Path.GetRelativePath(contentRootDir, HostPage!);
-			}
-
-			// If there is nothing to add (no AppType document and no manifest), return the platform
-			// provider unchanged to preserve existing behaviour exactly.
-			if (hostPageRelativePath is null && manifest is null)
-			{
-				return platformFileProvider;
-			}
+			// Render the host document once. This also collects any interactive components declared with
+			// a render mode and registers them so they attach to the live document, and resolves @Assets
+			// using the manifest.
+			EnsureAppTypeRendered(manifest?.Assets);
+			var hostPageRelativePath = Path.GetRelativePath(contentRootDir, HostPage!);
 
 			return new BlazorWebViewFileProvider(platformFileProvider, hostPageRelativePath, _renderedHostPageHtml, manifest);
 		}