Improved numeric parsing in Markdown files to surface errors instead of
defaulting to 0.0.
`export_csv` now uses `csv::Writer` to ensure RFC 4180 compliance (e.g.,
quoting fields containing commas).
`export_csv` now correctly respects the view's number format.
Add regression tests for numeric error handling and RFC 4180 compliance.
Co-Authored-By: fiddlerwoaroof/git-smart-commit (unsloth/gemma-4-26B-A4B-it-GGUF:UD-Q5_K_XL)
Edward Langley
47ad9e6032