The summary template puts the one-liner as a `**bold**` line after the
`# Phase N` heading, but `cmdSummaryExtract` and `cmdMilestoneComplete`
only checked frontmatter `one-liner` field — which is often empty.
Adds `extractOneLinerFromBody()` to core.cjs as a fallback that parses
the first `**...**` line after the heading.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>