Split usage docs into chapters and add MCP guide

Restructure docs/source, docs/source.zh-CN, docs/source.zh-TW so the
monolithic usage.rst becomes a usage/ section directory grouped by topic
(getting started, local & transfer, servers & integrations, reliability
& events, configuration & extension). Add a dedicated MCP chapter for
each language documenting Claude Desktop and Claude Code integration.

Author: JE-Chen

docs/source.zh-CN/index.rst

@@ -159,10 +159,10 @@ JSON 动作列表就是上述 list 的 list。
 
 .. toctree::
    :maxdepth: 2
-   :caption: 目录
+   :caption: 文档
 
    architecture
-   usage
+   usage/index
    api/index
 
 索引