refactor: 移除 SQLite 特有代码，完成 MySQL 迁移

src/vitals/core/database.py

@@ -4,7 +4,6 @@ import json
 import os
 from contextlib import contextmanager
 from datetime import date, time, datetime, timedelta
-from pathlib import Path
 from typing import Optional
 
 import mysql.connector
@@ -614,39 +613,23 @@ def ensure_default_user():
 
 
 def migrate_auth_fields():
-    """迁移：为现有 users 表添加认证字段"""
-    with get_connection() as conn:
-        cursor = conn.cursor()
+    """迁移：为现有 users 表添加认证字段（MySQL 版本）"""
+    with get_connection() as (conn, cursor):
+        # 检查列是否存在，MySQL 方式
+        cursor.execute("""
+            SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS
+            WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'users'
+        """)
+        columns = [row["COLUMN_NAME"] for row in cursor.fetchall()]
 
-        # 检查 users 表是否有 password_hash 列
-        cursor.execute("PRAGMA table_info(users)")
-        columns = [col["name"] for col in cursor.fetchall()]
-
-        # 添加缺失的列
         if "password_hash" not in columns:
-            cursor.execute("ALTER TABLE users ADD COLUMN password_hash TEXT")
+            cursor.execute("ALTER TABLE users ADD COLUMN password_hash VARCHAR(255)")
         if "email" not in columns:
-            cursor.execute("ALTER TABLE users ADD COLUMN email TEXT")
+            cursor.execute("ALTER TABLE users ADD COLUMN email VARCHAR(255)")
         if "is_admin" not in columns:
-            cursor.execute("ALTER TABLE users ADD COLUMN is_admin INTEGER DEFAULT 0")
+            cursor.execute("ALTER TABLE users ADD COLUMN is_admin TINYINT DEFAULT 0")
         if "is_disabled" not in columns:
-            cursor.execute("ALTER TABLE users ADD COLUMN is_disabled INTEGER DEFAULT 0")
-
-        # 检查 invites 表是否存在
-        cursor.execute("SELECT name FROM sqlite_master WHERE type='table' AND name='invites'")
-        if not cursor.fetchone():
-            cursor.execute("""
-                CREATE TABLE IF NOT EXISTS invites (
-                    id INTEGER PRIMARY KEY AUTOINCREMENT,
-                    code TEXT NOT NULL UNIQUE,
-                    created_by INTEGER NOT NULL,
-                    used_by INTEGER,
-                    created_at TEXT NOT NULL,
-                    expires_at TEXT,
-                    FOREIGN KEY (created_by) REFERENCES users(id),
-                    FOREIGN KEY (used_by) REFERENCES users(id)
-                )
-            """)
+            cursor.execute("ALTER TABLE users ADD COLUMN is_disabled TINYINT DEFAULT 0")
 
 
 # ===== 数据清除 =====