`_binding` C extension not built — `ModuleNotFoundError` on import

Hi, thanks for maintaining this grammar.

Installing from `main` and importing raises:

```
$ uv pip install git+https://github.com/Julian/tree-sitter-lean.git
$ python -c "import tree_sitter_lean; tree_sitter_lean.language()"
ModuleNotFoundError: No module named 'tree_sitter_lean._binding'
```

The installed package has `__init__.py` and `binding.c` but no compiled `_binding.so` — hatchling's wheel target packages the `.py` files but doesn't compile the C extension.

Repro: `main` at `30f05c80e`, Python 3.14, macOS arm64, uv.

For reference, `tree-sitter-cpp` and similar grammars use `setuptools` with a `setup.py` defining an `Extension` over `binding.c + src/parser.c + src/scanner.c`. Happy to send a PR if that'd be useful.

Inspect the hatchling wheel configuration and binding.c, then compare the setup.py Extension pattern used by tree-sitter-cpp and similar grammars. Verify the package built from main contains a compiled _binding extension and that the reported Python import command succeeds.

Written by the indexing model from the issue text.