docs: record default stable dingtalk image sending flow

TOOLS.md

@@ -127,4 +127,15 @@ await axios.post(url, body, { headers });
 - API: /v1.0/robot/groupMessages/send
 - ProcessQueryKey: lXs/uLRd0YxJVk1x0VyTLfSdY2YKCE1yrGn2vGlQ+GM=
 
+### 默认发图稳定流程（柏方确认）
+
+当用户说“发图”时，默认按以下顺序执行：
+
+1. `GET https://oapi.dingtalk.com/gettoken?appkey=...&appsecret=...` 获取 token
+2. `POST https://oapi.dingtalk.com/media/upload?access_token=...` 上传图片，获取 `media_id`
+3. `POST https://api.dingtalk.com/v1.0/robot/groupMessages/send` 发送消息
+   - Header: `x-acs-dingtalk-access-token: <token>`
+   - `msgKey = sampleMarkdown`
+   - `msgParam` 必须是 JSON 字符串（内嵌图片）
+
 Add whatever helps you do your job. This is your cheat sheet.