release: include the tag's CHANGELOG section in the Gitea release body

Previously the create-release POST sent only `{tag_name, name, draft,
prerelease}` — Gitea created the release with an empty description, so
users hitting the release page saw the tag name and nothing else.

Extracts the relevant `## [<version>]` block from CHANGELOG.md (using
$TAG with the leading `v` stripped) via awk, stopping at the next
`## [<other>]` section header or the trailing `[link-ref]: url` block,
and passes it as the `body` field to the release creation API.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -146,12 +146,20 @@ jobs:
           set -euo pipefail
           api="${GITHUB_SERVER_URL}/api/v1"
 
+          # Pull this tag's section out of CHANGELOG.md for the release body.
+          body=$(awk -v ver="${TAG#v}" '
+            $0 ~ "^## \\[" ver "\\]" { in_section=1; next }
+            in_section && /^## \[/ { exit }
+            in_section && /^\[.*\]:[[:space:]]/ { exit }
+            in_section
+          ' "$GITHUB_WORKSPACE/CHANGELOG.md")
+
           # Create the release (or get the existing one for this tag)
           release_json=$(curl -fsSL -X POST "$api/repos/$REPO/releases" \
               -H "Authorization: token $GITEA_TOKEN" \
               -H 'Content-Type: application/json' \
-              -d "$(jq -n --arg tag "$TAG" --arg name "$TAG" \
-                       '{tag_name:$tag,name:$name,draft:false,prerelease:false}')" \
+              -d "$(jq -n --arg tag "$TAG" --arg name "$TAG" --arg body "$body" \
+                       '{tag_name:$tag,name:$name,body:$body,draft:false,prerelease:false}')" \
               || curl -fsSL "$api/repos/$REPO/releases/tags/$TAG" \
                   -H "Authorization: token $GITEA_TOKEN")
           rid=$(echo "$release_json" | jq -r .id)