ci: extract release notes from commitizen-style changelog headings

The release-notes awk matched Keep-a-Changelog "## [X.Y.Z]" brackets, but
commitizen writes "## vX.Y.Z (date)", so every release body fell back to the
"Release vX.Y.Z" stub. Match the "## v" heading form instead so the release
carries its actual changelog section.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NGzHtDvJur9U7ysgRKRUTN

.gitea/workflows/release.yaml

@@ -85,7 +85,9 @@ jobs:
         run: |
           v="${{ steps.bump.outputs.version }}"
           # Body = this version's section from CHANGELOG.md (fallback to a stub).
-          body=$(awk "/^## \\[$v\\]/{f=1;next} /^## \\[/{f=0} f" CHANGELOG.md)
+          # Commitizen writes headings as "## vX.Y.Z (date)", so match that form
+          # (not the Keep-a-Changelog "## [X.Y.Z]" brackets) and stop at the next.
+          body=$(awk "/^## v$v/{f=1;next} /^## v/{f=0} f" CHANGELOG.md)
           [ -z "$body" ] && body="Release v$v"
           jq -n --arg tag "v$v" --arg name "v$v" --arg body "$body" \
             '{tag_name:$tag, name:$name, body:$body, draft:false, prerelease:false}' \