docs: standardize documentation with numpy-style docstrings

- Add comprehensive module-level docstrings to all flopyparser modules
- Convert all function/method docstrings to numpy documentation style
- Standardize parameter documentation with proper Parameters/Returns sections
- Enhance class docstrings with detailed descriptions and attributes
- Apply consistent formatting throughout codebase with ruff
- Improve code readability and maintainability

Changes include:
- flopyparser/__init__.py: Add package description
- flopyparser/flopyparser.py: Update CLI interface documentation
- flopyparser/model.py: Enhance Model class and method documentation
- flopyparser/parameter.py: Document Parameter class and utility functions
- flopyparser/metafunctions.py: Add processing function documentation
- flopyparser/version.py: Add version module description
- flopyparser/__main__.py: Document entry point module

Author: bdestombe

.gitignore

@@ -84,3 +84,5 @@ log.txt
 assets/IAH/Poster A22.pdf
 assets/IAH/~poster a2~pj2l-j.idlk
 assets/IAH/~workflow~2$wxpt.idlk
+.vscode/settings.json
+tests/mf executables