enhancement: improve Python and framework version management in project generation

[marcosgdz03]

Context

Python project generation already exists and allows selecting:

• Framework (Flask or FastAPI)
• Python version :contentReference[oaicite:1]{index=1}

However, version handling is limited and lacks flexibility.

Goal

Enhance version management and make it more robust and configurable.

Improvements

• Allow selecting:
  • Exact Python version (not just predefined list)
  • FastAPI version
  • Flask version
• Add "latest" option
• Add version compatibility validation

Functional Requirements

• Generate:
  • requirements.txt or pyproject.toml with selected versions
• Ensure virtualenv uses selected Python version
• Allow fallback to recommended versions

UX/UI

• Improve QuickPick:
  • Add version selector step for frameworks
  • Highlight stable versions
• Show warnings for incompatible combinations

Technical Considerations

• Fetch versions dynamically from PyPI
• Cache results locally for performance
• Maintain backward compatibility with current flow

Acceptance Criteria

• Users can select framework versions (not only Python)
• Generated dependencies match selected versions
• Project runs without version conflicts