[Placeholder] Adoption of Apache Iceberg Verification

Consider adopting [Apache Iceberg Verification](https://github.com/apache/iceberg-verification) once its initial fixtures are ready for integration. The project aims to provide shared, language-neutral conformance fixtures with expected values derived from the Iceberg specification, helping detect inconsistencies across implementations.

The original discussion ML thread: https://lists.apache.org/thread/8wsvnhktw27h0tqnxljzmnsogwd52tjj

从 Apache Iceberg Verification 仓库和链接的邮件列表讨论开始；issue 没有指定本地文件或测试。确认其初始 fixtures 已准备就绪，然后确定 iceberg-cpp 的集成入口点。当 iceberg-cpp 采用了共享的 verification fixtures 后，即表示完成。

由索引模型根据 Issue 内容生成。