feat: add py.typed marker and package-data for PEP 561 type checking support (#35)

* fix: update site URLs back to devforge after repo rename

* fix: add MIT license classifier to pyproject.toml, align package.json version with pyproject.toml

* style: apply UP038 — use X | Y in isinstance (requires Python >=3.10)

* fix: resolve mypy type errors (remove dead code, rename shadowed fpath variable)

* fix: add missing __init__.py to generators/ and parsers/ subpackages

* feat: add py.typed marker and package-data for PEP 561 type checking support

Author: Coding-Dev-Tools