Support @overload decorator generation

[konn]

What have been done in this PR?

• Supports @overload decorator for functions and methods.
• With this PR, now pyo3_stub_gen automatically adds @overloaded decorator when there are multiple PyFunctionInfo or MethodInfo for the same function/method (current main just picks the last submitted one).
  • If there is only one entry, it don't emit @overload.
  • It also adds import typing if needed.
• Fixes Function overloading #196.

[Copilot]

Pull Request Overview

This PR adds support for generating @overload decorators in Python stub files when multiple function or method signatures exist for the same name. The implementation automatically detects when there are multiple entries for the same function/method and generates appropriate @typing.overload decorators, while also ensuring the typing module is imported when needed.

• Converts single function/method storage to collections that support multiple signatures per name
• Adds automatic detection and generation of @typing.overload decorators
• Implements conditional import of the typing module when overloads are present

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
pyo3-stub-gen/src/generate/variant_methods.rs	Updates return type to use IndexMap for grouping methods by name
pyo3-stub-gen/src/generate/stub_info.rs	Adds overload tracking and converts function/method storage to support multiple signatures
pyo3-stub-gen/src/generate/module.rs	Implements overload decorator generation and conditional typing import
pyo3-stub-gen/src/generate/class.rs	Updates class method handling to support overloaded methods
examples/pure/tests/test_python.py	Adds test cases for overloaded functions and methods
examples/pure/src/lib.rs	Adds example implementations demonstrating overload functionality
examples/pure/pure.pyi	Shows generated stub file with overload decorators

[termoshtt]

LGTM