refactor(wechat_kf): rename channel from wechatcom_kf and split corp_id

Rename the WeCom customer-service channel and give it its own corp_id
field so users no longer have to share `wechatcom_corp_id` with the
self-built WeCom app channel.

Renames (channel-side):
- channel type / const: wechatcom_kf -> wechat_kf
- package dir: channel/wechatcom_kf/ -> channel/wechat_kf/
- python files / classes: WechatComKf* -> WechatKf*
- config keys: wechatcom_kf_{secret,token,aes_key,port} ->
  wechat_kf_{secret,token,aes_key,port}; new wechat_kf_corp_id
- env vars: WECHATCOM_KF_* -> WECHAT_KF_*; new WECHAT_KF_CORP_ID
- log prefix / cursor file: [wechatcom_kf] -> [wechat_kf]
- web console CHANNEL_DEFS key + startup log line

Renames (docs):
- docs/channels/wecom-kf.mdx -> docs/channels/wechat-kf.mdx (zh/en/ja)
- update docs.json sidebar entries and all field names inside the docs

In addition, the Web Console "微信客服" entry now exposes its own
Corp ID field instead of reusing the wechatcom_app one, and includes
the screenshot of the visual config in the channel guide.

Web Console onboarding section is added (Tabs: Web Console / config
file) and the local URL `http://127.0.0.1:9899/` parenthetical is
dropped for consistency with other channel docs.

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/ja/channels/wechat-kf.mdx

@@ -27,7 +27,7 @@ WeCom の自建アプリを「微信客服（WeCom Customer Service）」アカ
 
 <img src="https://cdn.link-ai.tech/doc/20260228103156.png" width="480"/>
 
-2. **自社情報** をクリックし、ページ下部で **企業ID（Corp ID）** を確認します（`wechatcom_corp_id` に設定します）：
+2. **自社情報** をクリックし、ページ下部で **企業ID（Corp ID）** を確認します（`wechat_kf_corp_id` に設定します）：
 
 <img src="https://cdn.link-ai.tech/doc/wechatcom-hosting-companyid.png" width="600"/>
 
@@ -58,22 +58,22 @@ WeCom の自建アプリを「微信客服（WeCom Customer Service）」アカ
 
     ```json
     {
-      "channel_type": "wechatcom_kf",
-      "wechatcom_corp_id": "YOUR_CORP_ID",
-      "wechatcom_kf_secret": "YOUR_SECRET",
-      "wechatcom_kf_token": "YOUR_TOKEN",
-      "wechatcom_kf_aes_key": "YOUR_AES_KEY",
-      "wechatcom_kf_port": 9888
+      "channel_type": "wechat_kf",
+      "wechat_kf_corp_id": "YOUR_CORP_ID",
+      "wechat_kf_secret": "YOUR_SECRET",
+      "wechat_kf_token": "YOUR_TOKEN",
+      "wechat_kf_aes_key": "YOUR_AES_KEY",
+      "wechat_kf_port": 9888
     }
     ```
 
     | パラメータ | 説明 |
     | --- | --- |
-    | `wechatcom_corp_id` | 企業 ID |
-    | `wechatcom_kf_secret` | カスタマーサービスにバインドした企業微信自建アプリの Secret |
-    | `wechatcom_kf_token` | API 受信設定の Token |
-    | `wechatcom_kf_aes_key` | API 受信設定の EncodingAESKey |
-    | `wechatcom_kf_port` | リスンポート、デフォルトは 9888 |
+    | `wechat_kf_corp_id` | 企業 ID |
+    | `wechat_kf_secret` | カスタマーサービスにバインドした企業微信自建アプリの Secret |
+    | `wechat_kf_token` | API 受信設定の Token |
+    | `wechat_kf_aes_key` | API 受信設定の EncodingAESKey |
+    | `wechat_kf_port` | リスンポート、デフォルトは 9888 |
   </Tab>
 </Tabs>