fix: fetcher 数据库路径可移植化（db.py get_conn 统一，去除 Windows 硬编码）

src/fetcher/cn_news_fetcher.py

@@ -1,13 +1,15 @@
 """A股新闻采集 - AkShare stock_news_em"""
 import warnings, logging, sqlite3
 from datetime import datetime
+from pathlib import Path
 import pandas as pd
+from src.storage.db import get_conn
 import akshare as ak
 
 logging.basicConfig(level=logging.INFO, format='%(asctime)s %(levelname)s %(message)s')
 log = logging.getLogger(__name__)
 
-DB = r'C:\Users\lookt\a_stock_timeline\data\a_stock.db'
+DB = str(Path(__file__).resolve().parent.parent.parent / 'data' / 'a_stock.db')
 
 def fetch_news():
     df = ak.stock_news_em(symbol='A股')
@@ -32,7 +34,7 @@ def fetch_news():
     df['inserted_at'] = datetime.now().isoformat()
     if 'id' not in df.columns:
         df.insert(0, 'id', range(1, len(df) + 1))
-    conn = sqlite3.connect(DB)
+    conn = get_conn()
     df.to_sql('news_cn', conn, if_exists='replace', index=False)
     conn.close()
     log.info(f'写入 news_cn: {len(df)} 行')