Fix: IP Scanner: Title of web pages with a code page charset (R17)

Encoding.GetEncoding threw for charsets that are not built into .NET
(windows-1252, iso-8859-2, shift_jis, gb2312, ...) because the
CodePagesEncodingProvider was not registered - the page was decoded as
UTF-8 (e.g. "B�ro-Drucker"). WebPageResolver registers it in its static
constructor.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: BornToBeRoot

Source/NETworkManager.Models/Network/WebPageResolver.cs

@@ -68,6 +68,15 @@ public static partial class WebPageResolver
         DefaultRequestHeaders = { { "User-Agent", "NETworkManager" } }
     };
 
+    /// <summary>
+    ///     Registers the code page encodings (e.g. <c>windows-1252</c>, <c>iso-8859-2</c>, <c>shift_jis</c>) for
+    ///     <see cref="Decode" /> - .NET only knows UTF-8 / UTF-16 / UTF-32, ASCII and ISO-8859-1 without them.
+    /// </summary>
+    static WebPageResolver()
+    {
+        Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
+    }
+
     [GeneratedRegex(@"<title[^>]*>(.*?)</title\s*>", RegexOptions.IgnoreCase | RegexOptions.Singleline)]
     private static partial Regex TitleRegex();
 

Source/NETworkManager.Tests/Network/WebPageResolverTests.cs

@@ -99,6 +99,27 @@ public void Decode_CharsetOfMetaTag()
         Assert.Equal(html, WebPageResolver.Decode(Encoding.Latin1.GetBytes(html), null));
     }
 
+    [Fact]
+    public void Decode_CodePageCharset()
+    {
+        // "Büro-Drucker €" in windows-1252 (not built into .NET, registered by WebPageResolver)
+        byte[] content =
+            [.. Encoding.ASCII.GetBytes("<title>B"), 0xFC, .. Encoding.ASCII.GetBytes("ro-Drucker "), 0x80,
+             .. Encoding.ASCII.GetBytes("</title>")];
+
+        Assert.Equal("<title>Büro-Drucker €</title>", WebPageResolver.Decode(content, "windows-1252"));
+    }
+
+    [Fact]
+    public void Decode_CodePageCharsetOfMetaTag()
+    {
+        byte[] content =
+            [.. Encoding.ASCII.GetBytes("<meta charset=\"windows-1252\"><title>B"), 0xFC,
+             .. Encoding.ASCII.GetBytes("ro</title>")];
+
+        Assert.Equal("<meta charset=\"windows-1252\"><title>Büro</title>", WebPageResolver.Decode(content, null));
+    }
+
     [Fact]
     public void Decode_UnknownCharset_UTF8()
     {