Feature/convert python environment to uv

[cuicaihao]

Summary
This PR provides a comprehensive modernization of the splitraster repository. It streamlines the developer workflow by migrating to modern Python tooling (uv,
ruff), standardizes the project structure, and enhances the documentation and CI/CD pipelines.

Key Changes

1. Tooling & Dependency Management

• Migrated to uv: Replaced standard pip workflows with uv for faster, more reliable dependency resolution and environment synchronization.
• Migrated to ruff: Replaced black and flake8 with ruff for unified, high-performance linting and formatting.
• Dependency Cleanup: Moved torch, torchvision, and pre-commit to development dependencies to keep the core library lightweight.
• Optional GIS Support: Added gdal as an optional dependency extra. Users can now install GIS support via pip install "splitraster[geo]".

2. Structural Refinement

• Standardized Testing:
  • Created a root-level tests/ directory.
  • Moved test assets to tests/data/ and updated .gitignore to prevent tracking processed outputs.
  • Moved test.py to tests/test_splitraster.py and updated it to use robust, relative paths.
• Boilerplate Removal: Deleted unused files from the original template (src/data/, test_environment.py, docs/sphinx/).
• Unified Documentation:
  • Moved CONTRIBUTING.md to the docs/ directory (supported by GitHub and MkDocs).
  • Consolidated the PyPI description to use PyPi.md while maintaining README.md for the repository landing page.

3. Documentation & Tutorials

• Renamed Notebooks: Updated tutorials to a more structured naming convention:
  • 01_Standard_Image_Tiling.ipynb
  • 02_GIS_GeoTIFF_Tiling.ipynb
• Path Synchronization: Updated all code snippets in README.md, docs/, and notebooks to point to the new ./tests/data/ paths.
• MkDocs Cleanup: Added a "Contributing" page to the site navigation and updated the site_url.

4. CI/CD Modernization

• Updated GitHub Actions (python-CI.yml and python-CD.yml) to:
  • Use ruff for linting and formatting checks.
  • Use PEP 517 python -m build for package creation instead of the outdated setup.py.
  • Target Python versions 3.10 through 3.13.

Verification Results

• Linting: ruff check . and ruff format . pass cleanly.
• Tests: All tests in tests/test_splitraster.py pass successfully via pytest tests/.
• Build: Package builds correctly using uv build (producing .whl and .tar.gz).
• Docs: mkdocs build runs without warnings.