Migrate build system from setuptools to hatchling

[fundthmcalculus]

Summary

This PR migrates the project's build system from setuptools to hatchling, updates project dependencies, and specifies Python 3.12 as the target version.

Key Changes

• Build system migration: Replaced setuptools with hatchling as the build backend

  • Updated build-system.requires to use hatchling instead of setuptools>=42 and wheel
  • Changed build-backend from setuptools.build_meta to hatchling.build
  • Replaced setuptools configuration with hatchling-specific build target configuration

• Dependency management:

  • Moved cloudpickle and sympy from samples/requirements.txt to core project dependencies
  • These are now listed in the main dependencies array in pyproject.toml

• Python version: Added .python-version file specifying Python 3.12 as the target version

Implementation Details

• The hatchling build configuration explicitly specifies packages to include: src/optimizers and src/fuzzy
• This replaces the previous setuptools dynamic package discovery and package-data configuration
• The migration maintains the same source directory structure (src/) while using a more explicit package declaration approach

https://claude.ai/code/session_01S4sf53AWr1qzmZSdDBo72p