Normalize u pressure fields from data instead of assuming fixed range

[nikolasborrel]

Refactor data generators and improve CI performance

Data Generator Refactoring

Pressure normalization improvements:

• Auto-calculate min/max pressure values from datasets (up to 500 samples)
• Add u_pressures(idx) method for consistent normalized pressure retrieval
• Remove hardcoded (-2.0, 2.0) assumption

Code quality:

• Remove simple property getters, use public attributes directly
• Extract shared normalization logic into helper functions
• Add type annotations for class attributes

PEP 8 compliance:

• Rename methods to snake_case (normalizeSpatial → normalize_spatial, etc.)

Testing

• Added unit tests for new functionality