docs: add INSPECT WAREHOUSE SQL reference

[sundy-li]

Summary

• add SQL reference pages for INSPECT WAREHOUSE in English and Chinese
• link the new command from the Warehouse index pages

Why

INSPECT WAREHOUSE is implemented in Databend, but the SQL reference site did not have a dedicated command page.

Verification

• matched the syntax and output columns against the Databend parser and interpreter
• ran git diff --check
• did not run a docs build locally because node_modules is not installed in this environment

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Project	Deployment	Actions	Updated (UTC)
docs	Ready	Preview, Comment	Apr 17, 2026 1:46am
docs-cn	Ready	Preview, Comment	Apr 17, 2026 1:46am

[bohutang]

文档中输出列名与源码 schema 不一致：

• 文档写的 node → 源码是 node_name（见 InspectWarehousePlan::schema() 中 DataField::new("node_name", ...)）
• 文档写的 type → 源码是 node_type（见 DataField::new("node_type", ...)）

中英文文档都需要修改。