GetUpdatedChangelog returns the updated changelog, grouped by version headers.

InitChangelog creates a new changelog file with a placeholder entry.

ParseChangelog loads a changelog file at the given path and returns a slice of strings containing changelog entries from the specified version.

ReadFile loads a changelog file at the given path and returns a slice of strings containing each line.

RenderCommits takes a slice of commits and returns a markdown-formatted string, including the category header.

ResolveChangelogFile returns the absolute path to the changelog file.

SplitIntoSections takes a slice of changelog lines and splits it into boilerplate and body sections.

WriteChangelog updates the changelog file with the given content.