Refactoring of Seata samples

## Refactoring of Seata samples

### Description:
- Seata samples is an important way for developers to learn and use Seata. Improving the ease of use of seata-samples will effectively reduce the learning threshold of developers

### Tasks:
- optimize the module structure of samples; optimize maven dependency management and code style.
- add samples readme guide document.

### Difficulty
- Basic

### Mentor
- ZhiJian Tan (@tanzzj , [zhijian.tzj@alibabac-inc.com](mailto:zhijian.tzj@alibabac-inc.com)), ASoC Mentor, Top contributor of Seata.

### Programming language:
- Java

---

## seata-samples 重构

### 描述：
- seata-samples 是开发者学习和使用 Seata 的重要途径。提升seata-samples的易用性，将有效降低开发者的学习门槛。

### 任务：
- 整理 samples 的模块结构，统一 maven 依赖管理和代码风格。
- 增加sample readme 指引文档。

### 难度
- 基础

### 导师
- ZhiJian Tan (@tanzzj , [zhijian.tzj@alibabac-inc.com](mailto:zhijian.tzj@alibabac-inc.com)), ASoC Mentor, Top contributor of Seata.

### 编程语言：
- Java

The issue names no specific files or tests. Start by inventorying the sample module structure and Maven dependency files, then review the existing sample documentation and code style. Done means the modules and dependencies are consistently organized, the style is aligned, and a README guide covers how to use the samples.

Written by the indexing model from the issue text.