feat: 添加 AI Agent 对话测试工具 + 代码优化

主要变更:

- 新增 tests/test_ai_chat.py: AI Agent 对话测试工具

- 优化 core/pydantic_ai_agent.py 和 db/chat_log_db.py

- 清理归档文件，更新文档

Made-with: Cursor

scripts/chat_log_viewer.py

@@ -177,17 +177,8 @@ def cmd_live(refresh: int = 3):
 
     try:
         while True:
-            import sqlite3
-            conn = sqlite3.connect(db._DB_PATH)
-            conn.row_factory = sqlite3.Row
-            rows = conn.execute("""
-                SELECT id, customer_id, customer_name, direction, message, timestamp
-                FROM chat_logs
-                ORDER BY id DESC LIMIT 20
-            """).fetchall()
-            conn.close()
-
-            new_rows = [dict(r) for r in rows if r["id"] not in seen_ids]
+            rows = db.get_latest_messages(20)
+            new_rows = [r for r in rows if r["id"] not in seen_ids]
             if new_rows:
                 new_rows.reverse()
                 for r in new_rows: