Run Python-to-R file workflows from the project root

[mhasoba]

Summary

• run the Python chapter R subprocess examples from the coursework project root
• update fmr.R and test_r.py to use data/, code/, and results/ consistently
• remove resolved runtime-path exceptions
• extend the clean-project R workflow check to cover both examples

Validation

• Rscript scripts/check_r_file_workflows.R
• python3 scripts/check_foundational_workflows.py
• seven content/runtime checker unit tests
• content check: 0 issues
• runtime path check: 0 issues
• notebook JSON and whitespace checks
• full make test book build (completed with 17 existing warnings)

[mhasoba]

approved