Merge pull request #32 from jlevy/codex/release-v0.4.0

docs: prepare v0.4.0 release

Merge pull request #17 from jlevy/claude/bold-clarke-uVwIn

DocGraph node model + v0.3.1 release prep

Merge pull request #11 from jlevy/claude/prepare-v0.3.0-release

Prepare v0.3.0 release (changelog + release process + clean-release fixes)

Convenience func for Markdown footnotes.

Merge pull request #2 from jlevy/new-html-tags

Improved html tag find/replace with selectolax.

Upgrade to flowmark v0.5.3.

Add missing exports.

Add attrs support to `div_wrapper`.

Minor cleanup to allow None as DiffFilter.

Linting/typing fixes.