Migrate static metadata to pyproject.toml for improved packaging standards

[dnerini]

The current setup.py-based installation is fully functional, but it could benefit from adopting pyproject.toml to follow modern packaging standards (PEP 517/518). This doesn't require removing setup.py, instead, we can gradually migrate static metadata and build requirements to a pyproject.toml while keeping the install scripts in setup.py, if needed.

# Motivation

• Standardization: pyproject.toml is the officially recommended way to define build systems and package metadata.
• Tool compatibility: Improves compatibility with modern packaging tools like uv.
• Cleaner separation: Metadata becomes declarative and easier to manage, while setup.py can be reserved for the custom install logic.
• Better developer experience: IDEs, linters, formatters, and test runners already use pyproject.toml for config, this aligns build configuration with that.