Cleanup legacy build files and add Makefile for tooling

[JaskRendix]

PR removes legacy setup.py and setup.cfg files, relying solely on pyproject.toml for build and packaging metadata. A Makefile is added to streamline developer workflows with common targets like build, publish, install, and test.

Fixed package discovery in pyproject.toml for editable installs: updated [tool.setuptools.packages.find] section:

where = ["."]
include = ["pyscroll"]

previously, include = ["pyscroll*"] caused setuptools to misidentify the package during pip install -e ., leading to ModuleNotFoundError, the new configuration ensures pyscroll is reliably discovered and included in builds and editable installs. Now editable install works as expected, import pyscroll resolves correctly across the project