feat: 添加 OAuth 认证支持及相关改进

- 新增 OAuth 模块，支持 LinuxDo/GitHub/Google 等第三方登录
- 用户邮箱改为可选字段，支持无邮箱注册
- 新增模块配置验证状态 (config_validated/config_error)
- 系统设置界面改为分块独立保存
- 用户设置新增 OAuth 绑定管理和首次密码设置
- 登录界面支持 OAuth 按钮展示
- 邮箱验证设置移至邮件设置页面

src/services/cache/user_cache.py

@@ -126,9 +126,11 @@ class UserCacheService:
         return {
             "id": user.id,
             "email": user.email,
+            "email_verified": user.email_verified,
             "username": user.username,
             "role": user.role.value if user.role else None,
             "is_active": user.is_active,
+            "auth_source": user.auth_source.value if user.auth_source else None,
             "quota_usd": float(user.quota_usd) if user.quota_usd is not None else None,
             "used_usd": float(user.used_usd),
             "created_at": user.created_at.isoformat() if user.created_at else None,
@@ -146,11 +148,13 @@ class UserCacheService:
         """
         from datetime import datetime
 
+        from src.core.enums import AuthSource
         from src.models.database import UserRole
 
         user = User(
             id=user_dict["id"],
-            email=user_dict["email"],
+            email=user_dict.get("email"),
+            email_verified=user_dict.get("email_verified", False),
             username=user_dict["username"],
             is_active=user_dict["is_active"],
             used_usd=user_dict["used_usd"],
@@ -160,6 +164,9 @@ class UserCacheService:
         if user_dict.get("role"):
             user.role = UserRole(user_dict["role"])
 
+        if user_dict.get("auth_source"):
+            user.auth_source = AuthSource(user_dict["auth_source"])
+
         if user_dict.get("quota_usd") is not None:
             user.quota_usd = user_dict["quota_usd"]