[Tutorial] CTable copy() with reblocking and recompression

The CTable.copy() method gained new chunks=, blocks=, and cparams= overrides in this release, but there is no tutorial showing when and why you would use them. There is a standalone example at examples/ctable/copying.py, but no notebook integrated into the tutorial sequence.

Suggested work: Add a notebook 16.ctable-copy.ipynb to doc/getting_started/tutorials/ covering:
- Basic in-memory and persistent copy
- Reblocking: how block size affects SUMMARY index granularity and query pruning
- Recompression: switching codecs (ZSTD → LZ4) and what to expect on size vs speed
- Copying a projected view (select().copy()) to persist a column subset

从 examples/ctable/copying.py 和 doc/getting_started/tutorials/ 下现有的序列开始。添加 doc/getting_started/tutorials/16.ctable-copy.ipynb，涵盖内存中复制和持久化复制、reblocking 和 SUMMARY 查询剪枝、从 ZSTD 重新压缩为 LZ4 的权衡，以及复制一个投影后的 select() 视图。完成的标准是该 notebook 已集成到教程序列中，并演示每个列出的案例。

由索引模型根据 Issue 内容生成。