Java multi-language blockchain exchange development: support fiat OTC, coin trading, contract leverage features

This update adds and optimises a number of features

引入了多国的语言支持、快速合约操作功能，并修复了K线图表相关问题

A detailed installation guide is provided along with the source code, and the front-end is partially developed using the Vue framework.

Below are screenshots showing the update

此次升级旨在提升用户体验，同时确保系统的稳定性和功能性。新增的多国的语言选项让全球用户能够更便捷地使用平台，而秒合约功能则极大简化了交易流程，使操作更加高效。

For the problems that existed in the K-line display in the previous version, we have carried out a comprehensive repair to ensure the accuracy and smoothness of the data display. In addition, the source package comes with complete installation instructions, developers can easily get started, the front-end code is based on the Vue framework to facilitate secondary development and maintenance.