NodeInfo is read as Mobilizon serves it

Mobilizon sends its NodeInfo as `application/json; profile=http://…#` with the URL unquoted, which .NET cannot parse,
so the document was refused for its content type and the server never described; and it names its software
"Mobilizon" where NodeInfo wants lower case. The media type is now read from the raw header when the parsed one is
missing, and software names are lowercased, so one software is counted under one name.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

PrivaPub/Federation/Objects/InstanceDocuments.cs

@@ -47,9 +47,10 @@ namespace PrivaPub.Federation.Objects
 			var usage = Section(root, "usage");
 			var users = Section(usage, "users");
 			var metadata = Section(root, "metadata");
+			// (NodeInfo wants the name in lower case; Mobilizon says "Mobilizon")
 			return new NodeInfoFacts(
 				version,
-				Text(software, "name", 200),
+				Text(software, "name", 200)?.ToLowerInvariant(),
 				Text(software, "version", 200),
 				Text(metadata, "nodeName", 200),
 				Plain(Text(metadata, "nodeDescription", 2000), 500),