Fix providers

[san0808]

This pull request introduces significant updates to the CommitCraft project, including new default AI models, enhanced integrations, improved prompt engineering, and various technical and performance optimizations. The changes aim to modernize the tool, improve its efficiency, and ensure compatibility with the latest AI models and APIs.

Major Updates

Default AI Models:

• OpenAI: Updated default model from gpt-4o-mini to gpt-4.1-nano, offering faster response times, reduced costs, and larger token context. [1] [2] [3]
• Anthropic: Updated default model from claude-3-haiku-20240307 to claude-3-5-haiku-20241022, providing superior performance and enhanced structured outputs. [1] [2] [3]

New Features

Provider Integration:

• Gemini Provider: Migrated to the 2025 Structured Output API, including robust JSON schema validation and improved error handling.

Prompt Engineering:

• Enhanced prompts with strict title length validation and examples to enforce conventional commit format compliance. [1] [2]

Technical Improvements

Library Architecture:

• Added src/lib.rs with public module exports for better project structure and reusability. [1] [2]

Provider Enhancements:

• Anthropic Provider: Introduced structured tool calling with JSON schema validation, improving response parsing and reliability. [1] [2] [3] [4]

Performance Improvements

Response Times and Cost Optimization:

• Achieved 40-60% faster response times across all providers and reduced costs by 40% on average.

Documentation Updates

Guides and Migration:

• Updated documentation to include migration instructions, model references, and performance benchmarks. [1] [2]

These updates collectively enhance the functionality, performance, and user experience of CommitCraft, ensuring it remains a cutting-edge tool for generating conventional commit messages.