CHANGELOG.md: one line per change, and what each site runs

Forty releases carried only a version bump in their commit, so what
changed lived in the commits between them and in the content repos'
pin bumps. The changelog is reconstructed from that history, newest
first, with an Unreleased section on top and a table of which version
each of the four sites runs. The publish workflow now posts the tag's
section as the Gitea release notes, and the README says to move the
Unreleased lines under a version heading before cutting.

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

.gitea/workflows/publish.yml

@@ -88,9 +88,9 @@ jobs:
           tag="${{ github.ref_name }}"
           api="${{ github.server_url }}/api/v1/repos/${{ github.repository }}"
           auth="Authorization: token ${{ secrets.GITHUB_TOKEN }}"
-          subject=$(git log -1 --format=%s)
-          body=$(printf '{"tag_name":"%s","name":"%s"}' \
-            "$tag" "$tag: $(echo "$subject" | sed 's/"/\\"/g')")
+          # The release notes are this version's section of CHANGELOG.md.
+          notes=$(awk -v v="${tag#v}" '/^## /{p = ($2 == v)} p' CHANGELOG.md | tail -n +2)
+          body=$(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" "$api/releases" | jq .id) \
             || id=$(curl -sf -H "$auth" "$api/releases/tags/$tag" | jq .id)