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>

channel/wechat_kf/wechat_kf_message.py

@@ -0,0 +1,82 @@
+# -*- coding=utf-8 -*-
+"""
+Adapter that turns a single `sync_msg` item from WeCom customer-service
+into a CoW `ChatMessage` object.
+"""
+from wechatpy.enterprise import WeChatClient
+
+from bridge.context import ContextType
+from channel.chat_message import ChatMessage
+from common.log import logger
+from common.tmp_dir import TmpDir
+
+
+class WechatKfMessage(ChatMessage):
+    """
+    msg structure (from cgi-bin/kf/sync_msg):
+        {
+          "msgid": "...",
+          "send_time": 1700000000,
+          "origin": 3,
+          "msgtype": "text" | "image" | "voice" | ...,
+          "open_kfid": "wkxxxx",
+          "external_userid": "wmxxxx",
+          "text": {"content": "..."},
+          "image": {"media_id": "..."},
+          "voice": {"media_id": "..."},
+          ...
+        }
+    """
+
+    def __init__(self, msg: dict, client: WeChatClient = None, is_group: bool = False):
+        # NOTE: skip parent constructor because it expects a wechatpy parsed
+        # message object, while here we receive a raw dict from sync_msg.
+        super().__init__(msg)
+        self.is_group = is_group
+        self.msg_id = msg.get("msgid")
+        self.create_time = msg.get("send_time")
+        self.origin = msg.get("origin")
+        self.msgtype = msg.get("msgtype")
+        self.open_kfid = msg.get("open_kfid")
+        self.external_userid = msg.get("external_userid")
+
+        if self.msgtype == "text":
+            self.ctype = ContextType.TEXT
+            self.content = msg.get("text", {}).get("content", "")
+        elif self.msgtype == "image":
+            self.ctype = ContextType.IMAGE
+            media_id = msg.get("image", {}).get("media_id", "")
+            self.content = TmpDir().path() + media_id + ".jpg"
+
+            def download_image():
+                response = client.media.download(media_id)
+                if response.status_code == 200:
+                    with open(self.content, "wb") as f:
+                        f.write(response.content)
+                else:
+                    logger.info(f"[wechat_kf] Failed to download image, {response.content}")
+
+            self._prepare_fn = download_image
+        elif self.msgtype == "voice":
+            self.ctype = ContextType.VOICE
+            media_id = msg.get("voice", {}).get("media_id", "")
+            # WeCom returns amr by default; downstream voice pipeline will convert.
+            self.content = TmpDir().path() + media_id + ".amr"
+
+            def download_voice():
+                response = client.media.download(media_id)
+                if response.status_code == 200:
+                    with open(self.content, "wb") as f:
+                        f.write(response.content)
+                else:
+                    logger.info(f"[wechat_kf] Failed to download voice, {response.content}")
+
+            self._prepare_fn = download_voice
+        else:
+            raise NotImplementedError(
+                f"[wechat_kf] Unsupported message type: {self.msgtype}"
+            )
+
+        self.from_user_id = self.external_userid
+        self.to_user_id = self.open_kfid
+        self.other_user_id = self.external_userid