feat: package dockreap as proper Python CLI and update README

- Add pyproject.toml for setuptools-based packaging
- Rename entrypoint to dockreap.__main__ and expose console script
- Update README with pip/pipx installation instructions
- Remove obsolete package-manager references
- Add MIRRORS file including PyPI endpoint
- Align documentation with actual volume usage detection logic

pyproject.toml

@@ -0,0 +1,36 @@
+[build-system]
+requires = ["setuptools>=69", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "dockreap"
+version = "0.0.0"
+description = "Remove unused anonymous Docker volumes (with symlink cleanup)."
+readme = "README.md"
+requires-python = ">=3.9"
+license = { text = "MIT" }
+authors = [{ name = "Kevin Veen-Birkenbach" }]
+keywords = ["docker", "volumes", "cleanup", "devops"]
+classifiers = [
+  "License :: OSI Approved :: MIT License",
+  "Programming Language :: Python :: 3",
+  "Programming Language :: Python :: 3 :: Only",
+  "Environment :: Console",
+  "Operating System :: POSIX :: Linux",
+  "Topic :: System :: Systems Administration",
+]
+
+dependencies = []
+
+[project.urls]
+Homepage = "https://www.veen.world/"
+Repository = "https://github.com/kevinveenbirkenbach/dockreap"
+
+[project.scripts]
+dockreap = "dockreap.__main__:main"
+
+[tool.setuptools]
+package-dir = { "" = "src" }
+
+[tool.setuptools.packages.find]
+where = ["src"]