CLI rename to gdiff-unstaged and gdiff-pr

• Add .pyproject.toml to standardize the build system for the package, specifying build requirements and backend.
• Update setup.py, bumping version to 0.0.2 and refining the console script paths to include the new gptassist namespace, improving package structure and CLI accessibility.
• Introduce documentation on Conventional Commits to guide commit message standards in assets/git-msg-convention.md, aiding in consistent and meaningful commit practices.
• Create prompts for enhancing interaction with Git through ChatGPT, providing structured guidelines for generating commit messages and reviewing code changes, detailed in prompts/chat-readme-md.md and prompts/gpts-copilot-code-review-n-commit-msg-agent.md.
• Reorganize CLI tools into gptassist namespace, encapsulating functionality related to Git diff processing and unstaged changes logging, ensuring a clean package structure and namespace usage.

This series of changes not only streamlines the build and setup process of the package but also enhances the tooling around Git operations with ChatGPT, promoting better development practices and integration.