feat: 添加管理员密码修改功能

src/LiveRecorder.Application/Services/AuthService.cs

@@ -112,4 +112,31 @@ public sealed class AuthService : IAuthService
             ExpiresAt = session.ExpiresAt
         };
     }
+
+    public async Task ChangePasswordAsync(Guid userId, ChangePasswordRequest request, CancellationToken cancellationToken = default)
+    {
+        ArgumentNullException.ThrowIfNull(request);
+
+        if (string.IsNullOrWhiteSpace(request.CurrentPassword) || string.IsNullOrWhiteSpace(request.NewPassword))
+        {
+            throw new InvalidOperationException("当前密码和新密码不能为空。");
+        }
+
+        if (request.NewPassword.Length < 6)
+        {
+            throw new InvalidOperationException("新密码长度不能少于 6 位。");
+        }
+
+        var user = await _userAccountRepository.GetByIdAsync(userId, cancellationToken)
+            ?? throw new InvalidOperationException("用户不存在。");
+
+        if (!PasswordHasher.Verify(request.CurrentPassword, user.PasswordHash))
+        {
+            throw new InvalidOperationException("当前密码不正确。");
+        }
+
+        user.UpdatePassword(PasswordHasher.Hash(request.NewPassword));
+        _userAccountRepository.Update(user);
+        await _unitOfWork.SaveChangesAsync(cancellationToken);
+    }
 }