ci: release 通知 step 去掉 jq 依赖

之前用 jq -n --arg 拼 JSON payload, 依赖 runner 镜像预装 jq.
Gitea act_runner 镜像可以自定义 (alpine / distroless / 极简
ubuntu), 不一定带 jq. 一旦缺, release 通知 step 静默失败
(curl 仍然发但 payload 是空字符串, Bark 端按 400/500 处理),
release 仍然成功上传但 user 收不到通知.

改用 heredoc 直接展开 shell 变量拼 JSON:
  PAYLOAD=$(cat <<EOF
  { "device_key": "...", "title": "${TITLE}", ... }
  EOF
  )

TITLE (tag 名, 形如 v0.0.1-beta) 和 BODY (release URL, 只含
https URL + tag 字符串) 都没有 ", \, 控制字符, heredoc 展开
安全. 不需要 jq 转义.

这一步跟 release upload 串行 (release job 本身顺序 steps), Bark
通知仍然是 release 成功的最后一步, if: success() 保留.

Co-Authored-By: Claude <noreply@anthropic.com>

.github/workflows/build.yml

@@ -82,18 +82,18 @@ jobs:
         run: |
           TITLE="${{ github.ref_name }}"
           BODY="spark-mcp ${TITLE} released: ${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY}/releases/tag/${TITLE}"
+          PAYLOAD=$(cat <<EOF
+          {
+            "device_key": "6ZFVsxM95cuAjYoNLWSWaN",
+            "title": "${TITLE}",
+            "body": "${BODY}",
+            "group": "backup",
+            "isArchive": 1,
+            "ttl": 3600
+          }
+          EOF
+          )
           curl -s \
             -X POST http://101.43.40.124:81/push \
             -H "Content-Type: application/json; charset=utf-8" \
-            -d "$(jq -n \
+            -d "${PAYLOAD}"
-                --arg device_key "6ZFVsxM95cuAjYoNLWSWaN" \
-                --arg title "$TITLE" \
-                --arg body "$BODY" \
-                '{
-                    device_key: $device_key,
-                    title: $title,
-                    body: $body,
-                    group: "backup",
-                    isArchive: 1,
-                    ttl: 3600
-                }')"