fix: correct package structure for type stubs to resolve import-untyped errors

- Rename nameparser_stubs/ to nameparser/ to match actual module name
- Update pyproject.toml package configuration
- Add py.typed file to signal package contains type information

This fixes the [import-untyped] error that occurs when installing the
package, as type stubs must be in a package that matches the module
name that users import (nameparser, not nameparser_stubs).

Author: LucianBuzzo

nameparser_stubs/__init__.pyi nameparser/__init__.pyinameparser_stubs/__init__.pyi renamed to nameparser/__init__.pyi

@@ -33,8 +33,8 @@ classifiers = [
 ]
 
 [tool.setuptools]
-packages = ["nameparser_stubs"]
-package-data = {"nameparser_stubs" = ["*.pyi"]}
+packages = ["nameparser"]
+package-data = {"nameparser" = ["*.pyi"]}
 
 [dependency-groups]
 dev = [