feat(config): add sensitive word filtering system with database support

Implement sensitive word filtering feature with configurable database and Redis
support. Add security enhancements including WebSocket origin validation, improved
password strength requirements, timing attack prevention, and production JWT secret
validation. Add batch operation validation limits and optimize user blocking
queries with subqueries.

BREAKING CHANGE: Password validation now requires minimum 8 characters with uppercase,
lowercase, and digit (was 6-50 characters without complexity requirements)

internal/service/user_service.go

@@ -278,6 +278,9 @@ func (s *userServiceImpl) Login(ctx context.Context, account, password string) (
 	var failReason string
 
 	if err != nil || user == nil {
+		// 时序攻击防护：执行假的密码哈希验证，保持响应时间一致
+		_ = utils.CheckPasswordHash(password, "$2a$10$fakehashfortimingattackprevention1234567890")
+
 		loginResult = string(model.LoginResultFail)
 		failReason = string(model.FailReasonUserNotFound)