- Add SourceLocation struct (XNeedle namespace) with FilePath, Encoding,
and LineNumber (-1 sentinel when unavailable)
- Add SLoc property to Context; Clone() propagates it for free
- Expose XmlRoundtripWriter.DetectEncoding as internal static
- Add XmlRoundtripWriter.CreateToString(filePath, encoding) returning a
(writer, StringBuilder) tuple for in-memory style-preserving rendering
- Update XmlFragParser.ChecksumData to accept tagName only; use
OpeningTagAnchor to skip the opening tag robustly, and AnyChar.Until()
to non-greedily capture content through the closing tag
- Thread SourceLocation from Program.cs through Rule.Transform/Operate,
refreshing LineNumber per node via IXmlLineInfo
- Implement ContextFunctions.crc: render node via CreateToString, extract
digest slice via ChecksumData, encode with SLoc.Encoding, return CRC32
as double for arithmetic compatibility
Clanker: claude-sonnet_4.6
