docs: clarify Python module responsibilities

Rewrite the module-level descriptions for all 28 Python files and remove the obsolete integration note from grok_register_ttk.py. Verified on Python 3.9 and Python 3.12.

cpa_xai/browser_session.py

@@ -1,4 +1,4 @@
-"""CPA Chromium session lifecycle, reuse, cleanup, and cookies."""
+"""管理 CPA 授权浏览器会话、代理、Cookie 注入和资源清理。"""
 from __future__ import annotations
 
 import os