docs(README.md): restructure README, move CLI setup instructions to top for better visibility
feat(cli.cjs): extend file exclusion list in 'getDiff' to include image files for better performance
refactor(config.ts): add more model options in configValidators for flexibility
refactor(config.ts): set default model to 'gpt-3.5-turbo-16k' for better performance
refactor(git.ts): simplify 'getCoreHooksPath' function for readability
feat(git.ts): extend file exclusion list in 'getDiff' to include image files for better performance
