docs: consolidate contribution guides into single unified guide

Merge community_contribution_guide.adoc and ecosystem_contribution_guide.adoc
into a single contribution_guide.adoc for both Chinese and English versions.

Changes:
- Create unified contribution_guide.adoc combining all contribution content
- Remove separate community and ecosystem contribution guide files
- Update navigation in both CN and EN nav.adoc files
- Content covers: community workflow, roles, getting started, code contributions,
  and ecosystem component adaptation

This consolidation provides a single entry point for all contribution-related
information, eliminating content duplication and improving user experience.

Author: jiaoshuntian

CN/modules/ROOT/nav.adoc

@@ -80,8 +80,7 @@
 * 数据迁移
 ** xref:master/migration_guide.adoc[迁移指南]
 * IvorySQL开发者
-** xref:master/contribution/community_contribution_guide.adoc[社区贡献指南]
-** xref:master/contribution/ecosystem_contribution_guide.adoc[生态组件适配贡献指南]
+** xref:master/contribution/contribution_guide.adoc[贡献指南]
 ** xref:master/developer_guide.adoc[开发者指南]
 ** IvorySQL架构设计
 *** 查询处理