Add webmanifest MIME type to Wasm.web.config for PWA support

Co-authored-by: javiercn <[email protected]>

Author: Copilot

src/mono/nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Wasm.web.config

@@ -8,6 +8,7 @@
       <remove fileExtension=".webcil" />
       <remove fileExtension=".json" />
       <remove fileExtension=".wasm" />
+      <remove fileExtension=".webmanifest" />
       <remove fileExtension=".woff" />
       <remove fileExtension=".woff2" />
       <mimeMap fileExtension=".blat" mimeType="application/octet-stream" />
@@ -16,6 +17,7 @@
       <mimeMap fileExtension=".dat" mimeType="application/octet-stream" />
       <mimeMap fileExtension=".json" mimeType="application/json" />
       <mimeMap fileExtension=".wasm" mimeType="application/wasm" />
+      <mimeMap fileExtension=".webmanifest" mimeType="application/manifest+json" />
       <mimeMap fileExtension=".woff" mimeType="application/font-woff" />
       <mimeMap fileExtension=".woff2" mimeType="application/font-woff" />
     </staticContent>