refactor: 重构 API 接口模块，整合为 api_wrappers 目录结构

- 将独立 API 模块 (daily, stock_basic, trade_cal) 整合至 api_wrappers/
- 重写 sync.py 使用新的 wrapper 结构，支持更多同步功能
- 更新测试文件适配新的模块结构
- 添加 pytest.ini 配置文件

src/data/api_wrappers/__init__.py

@@ -0,0 +1,40 @@
+"""Tushare API wrapper modules.
+
+This package contains simplified interfaces for fetching data from Tushare API.
+All wrapper files follow the naming convention: api_{data_type}.py
+
+Available APIs:
+    - api_daily: Daily market data (日线行情)
+    - api_stock_basic: Stock basic information (股票基本信息)
+    - api_trade_cal: Trading calendar (交易日历)
+
+Example:
+    >>> from src.data.api_wrappers import get_daily, get_stock_basic, get_trade_cal
+    >>> data = get_daily('000001.SZ', start_date='20240101', end_date='20240131')
+    >>> stocks = get_stock_basic()
+    >>> calendar = get_trade_cal('20240101', '20240131')
+"""
+
+from src.data.api_wrappers.api_daily import get_daily
+from src.data.api_wrappers.api_stock_basic import get_stock_basic, sync_all_stocks
+from src.data.api_wrappers.api_trade_cal import (
+    get_trade_cal,
+    get_trading_days,
+    get_first_trading_day,
+    get_last_trading_day,
+    sync_trade_cal_cache,
+)
+
+__all__ = [
+    # Daily market data
+    "get_daily",
+    # Stock basic information
+    "get_stock_basic",
+    "sync_all_stocks",
+    # Trade calendar
+    "get_trade_cal",
+    "get_trading_days",
+    "get_first_trading_day",
+    "get_last_trading_day",
+    "sync_trade_cal_cache",
+]