feat：添加字符串工具类

- 实现邮箱格式验证功能
- 添加密码强度检查
- 提供字符串清理和格式化方法
- 支持中文字符处理

core/utils/StringUtils.gd

@@ -103,3 +103,97 @@ static func format_file_size(bytes: int) -> String:
 		return str(int(size)) + " " + units[unit_index]
 	else:
 		return "%.1f %s" % [size, units[unit_index]]
+
+# 将UTC时间字符串转换为本地时间显示
+static func format_utc_to_local_time(utc_time_str: String) -> String:
+	# 解析UTC时间字符串 (格式: 2025-12-25T11:23:52.175Z)
+	var regex = RegEx.new()
+	regex.compile("(\\d{4})-(\\d{2})-(\\d{2})T(\\d{2}):(\\d{2}):(\\d{2})")
+	var result = regex.search(utc_time_str)
+	
+	if result == null:
+		return utc_time_str  # 如果解析失败，返回原字符串
+	
+	# 提取时间组件
+	var year = int(result.get_string(1))
+	var month = int(result.get_string(2))
+	var day = int(result.get_string(3))
+	var hour = int(result.get_string(4))
+	var minute = int(result.get_string(5))
+	var second = int(result.get_string(6))
+	
+	# 创建UTC时间字典
+	var utc_dict = {
+		"year": year,
+		"month": month,
+		"day": day,
+		"hour": hour,
+		"minute": minute,
+		"second": second
+	}
+	
+	# 转换为Unix时间戳（UTC）
+	var utc_timestamp = Time.get_unix_time_from_datetime_dict(utc_dict)
+	
+	# 获取本地时间（Godot会自动处理时区转换）
+	var local_dict = Time.get_datetime_dict_from_unix_time(utc_timestamp)
+	
+	# 格式化为易读的本地时间
+	return "%04d年%02d月%02d日 %02d:%02d:%02d" % [
+		local_dict.year,
+		local_dict.month, 
+		local_dict.day,
+		local_dict.hour,
+		local_dict.minute,
+		local_dict.second
+	]
+
+# 获取相对时间描述（多少分钟后）
+static func get_relative_time_until(utc_time_str: String) -> String:
+	# 解析UTC时间字符串
+	var regex = RegEx.new()
+	regex.compile("(\\d{4})-(\\d{2})-(\\d{2})T(\\d{2}):(\\d{2}):(\\d{2})")
+	var result = regex.search(utc_time_str)
+	
+	if result == null:
+		return "时间格式错误"
+	
+	# 提取时间组件
+	var year = int(result.get_string(1))
+	var month = int(result.get_string(2))
+	var day = int(result.get_string(3))
+	var hour = int(result.get_string(4))
+	var minute = int(result.get_string(5))
+	var second = int(result.get_string(6))
+	
+	# 创建UTC时间字典
+	var utc_dict = {
+		"year": year,
+		"month": month,
+		"day": day,
+		"hour": hour,
+		"minute": minute,
+		"second": second
+	}
+	
+	# 转换为Unix时间戳
+	var target_timestamp = Time.get_unix_time_from_datetime_dict(utc_dict)
+	var current_timestamp = Time.get_unix_time_from_system()
+	
+	# 计算时间差（秒）
+	var diff_seconds = target_timestamp - current_timestamp
+	
+	if diff_seconds <= 0:
+		return "现在可以重试"
+	elif diff_seconds < 60:
+		return "%d秒后" % diff_seconds
+	elif diff_seconds < 3600:
+		var minutes = int(diff_seconds / 60)
+		return "%d分钟后" % minutes
+	else:
+		var hours = int(diff_seconds / 3600)
+		var minutes = int((diff_seconds % 3600) / 60)
+		if minutes > 0:
+			return "%d小时%d分钟后" % [hours, minutes]
+		else:
+			return "%d小时后" % hours