fix: MySQL 连���池添加重试逻辑

- 最多重试 30 次，每次间隔 2 秒
- 解决 MySQL 容器启动慢导致的连接失败问题
- 添加 import time 模块

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/vitals/core/database.py

@@ -2,6 +2,7 @@
 
 import json
 import os
+import time
 from contextlib import contextmanager
 from datetime import date, time, datetime, timedelta
 from typing import Optional
@@ -28,16 +29,33 @@ def get_mysql_config() -> dict:
 
 
 def init_connection_pool():
-    """初始化数据库连接池"""
+    """初始化数据库连接池（带重试）"""
     global _connection_pool
     if _connection_pool is None:
         config = get_mysql_config()
-        _connection_pool = pooling.MySQLConnectionPool(
-            pool_name="vitals_pool",
-            pool_size=5,
-            pool_reset_session=True,
-            **config
-        )
+        max_retries = 30
+        retry_delay = 2
+
+        for attempt in range(max_retries):
+            try:
+                _connection_pool = pooling.MySQLConnectionPool(
+                    pool_name="vitals_pool",
+                    pool_size=5,
+                    pool_reset_session=True,
+                    **config
+                )
+                # 测试连接
+                conn = _connection_pool.get_connection()
+                conn.close()
+                print(f"[Vitals] MySQL 连接池初始化成功")
+                return _connection_pool
+            except Exception as e:
+                if attempt < max_retries - 1:
+                    print(f"[Vitals] MySQL 连接失败，{retry_delay}秒后重试... ({attempt + 1}/{max_retries}): {e}")
+                    time.sleep(retry_delay)
+                else:
+                    print(f"[Vitals] MySQL 连接失败，已重试 {max_retries} 次")
+                    raise
     return _connection_pool