fix: 统一项目版本号并修复Maven Central发布配置

- 将父项目版本从2.0.5升级到2.0.6
- 移除子项目中的硬编码版本号，改为继承父项目版本
- 将内部依赖引用改为使用${project.version}变量
- 添加RELEASE-2.0.6.md发布说明文档

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Co-Authored-By: Claude <noreply@anthropic.com>

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>com.jhinno</groupId>
     <artifactId>jhinno-openapi-java-sdk-parent</artifactId>
-    <version>2.0.5</version>
+    <version>2.0.6</version>
     <packaging>pom</packaging>
     <name>Jhinno OpenAPI SDK for Java parent</name>
     <description>The Jhinno OpenAPI SDK for Java used for accessing Jhinno OpenApi Service</description>