CHANGELOG: the sections for 0.3.39 to 0.3.41; publish refuses a tag without one

Three releases went out with no section because the edit that moves
Unreleased under a version heading was a no-op when no Unreleased
section existed, and nothing checked. Now the publish job fails when
the tag has no section.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01L4jrCgLiKKHAEFuZUJjckH

.gitea/workflows/publish.yml

@@ -147,6 +147,7 @@ jobs:
           auth="Authorization: token ${{ secrets.GITHUB_TOKEN }}"
           # The release notes are this version's section of CHANGELOG.md.
           notes=$(awk -v v="${tag#v}" '/^## /{p = ($2 == v)} p' CHANGELOG.md | tail -n +2)
+          [ -n "$(printf "%s" "$notes" | tr -d "[:space:]")" ] || { echo "CHANGELOG.md has no section for $tag - write it and re-tag"; exit 1; }
           body=$(jq -n --arg tag "$tag" --arg notes "$notes" '{tag_name: $tag, name: $tag, body: $notes}')
           id=$(curl -sf -X POST -H "$auth" -H 'Content-Type: application/json' \
             -d "$body" "$api/releases" | jq .id) \