* fix(skills): support basename data-analysis exports
Use the current directory when export output has no parent directory.
* test(skills): cover data-analysis export paths
Exercise real DuckDB queries, filesystem exports and cached CLI execution across CSV, JSON and Markdown.
* docs(skills): record export path regression guidance
Document basename and nested output expectations and the regression test command.
* docs(skills): explain data-analysis export paths
Clarify bare filenames, relative parent directories and absolute output paths.
* docs: note supported data-analysis export paths
Add a concise README explanation while retaining existing upstream documentation.
* docs(skills): clarify export overwrite behavior
Document that existing export targets are overwritten without warning, as suggested in PR #7132. Verified real CSV, JSON and Markdown overwrites; 27 export regression tests pass.
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Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
