Allowed reading plain text and JSON from the web, with a stronger prompt injection filter (#1000)

app/MindWork AI Studio/Tools/HTMLParserWebPage.cs

@@ -1,5 +1,3 @@
-using HtmlAgilityPack;
-
 namespace AIStudio.Tools;
 
 public sealed class HTMLParserWebPage
@@ -10,5 +8,13 @@ public sealed class HTMLParserWebPage
 
     public required string ContentType { get; init; }
 
-    public required HtmlDocument Document { get; init; }
+    /// <summary>
+    /// The response body as text, as the server sent it.
+    /// </summary>
+    /// <remarks>
+    /// Kept as text rather than parsed, because what it is depends on the content type: an HTML
+    /// page is parsed by the retrieval service, while a JSON or plain text document must never
+    /// be, since an HTML parser would read every angle bracket in it as markup.
+    /// </remarks>
+    public required string Body { get; init; }
 }