v0.1.11 — inline HTML comments preserve prose

Second Codex-caught regression on the v0.1.9 commit-body feature.

v0.1.10 skipped HTML comments too aggressively — it dropped any line containing <!--, so content-bearing lines like Fix parser crash <!-- closes #42 --> lost their prose.

Fix in v0.1.11: awk now strips only the <!-- ... --> pairs themselves, preserving prose on the same line. Multi-line comment blocks still consumed across line boundaries; markdown headings still skipped. Content-only lines, comment-only lines, and hybrid lines all extract correctly now.

84/84 bats tests pass (+3 new cases).