feat: add dingtalk chat channel (#16183)

### What does this PR do?
This PR adds a new DingTalk chat channel integration and hardens the
inbound callback path.

### Summary
- Adds DingTalk as a selectable chat channel in the UI and backend
channel registry.
- Adds the DingTalk chat channel icon asset.
- Acknowledges DingTalk Stream callbacks and deduplicates repeated
inbound messages to avoid duplicate replies.

web/src/locales/en.ts

@@ -1497,6 +1497,7 @@ Example: Virtual Hosted Style`,
       chatChannelDesc: {
         clickclack: 'Connect a ClickClack bot',
         discord: 'Connect a Discord bot',
+        dingtalk: 'Connect a DingTalk bot',
         feishu: 'Connect a Feishu / Lark bot',
         googlechat: 'Connect a Google Chat bot',
         irc: 'Connect to an IRC server',

web/src/locales/zh.ts

@@ -1226,6 +1226,7 @@ NER：使用 spaCy NER 和基于规则的关键词提取来抽取实体和关系
       chatChannelDesc: {
         clickclack: '连接 ClickClack 机器人',
         discord: '连接 Discord 机器人',
+        dingtalk: '连接钉钉机器人',
         feishu: '连接飞书 / Lark 机器人',
         googlechat: '连接 Google Chat 机器人',
         irc: '连接 IRC 服务器',