[FIX] Avoid Python 3.14 regex escape warnings

[Mirochill]

Reference Issue

Fixes #179.

What does this implement/fix? Explain your changes.

• Converts the three regex literals reported in SyntaxWarnings with Python 3.14.2 #179 to raw strings, preserving the regex patterns.
• Updates both the nbdev notebooks and the generated Python modules.

Any other comments?

• Not run locally
• Static validation only: git diff --check, plus JSON parsing of the edited notebooks.