- Md (yaml+toml): tags now marshal as ["tag1", "tag2"] (quoted)
- Txt: tags now marshal as double-space-separated (tag1 tag2)
- Add parseTags() to Unmarshal: accepts any delimiter format and
normalizes each tag to [a-z0-9]+, enabling lenient frontmatter
input on body writes
- Fix results tests to use UnmarshalStrict where errors were expected
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>