0.4.5

The "rebuild" branch introduces a significant new feature called ReAct mode (Reasoning and Acting) to the Helios Engine, updating the crate version from 0.4.4 to 0.4.5.

Key Changes:
ReAct Mode Feature:

Added a simple .react() method to the agent builder pattern
Enables agents to reason about tasks before taking actions
Implements a two-phase approach: Reasoning → Action
Provides transparent reasoning output with the prefix "💭 ReAct Reasoning:"
Works seamlessly with all existing tools
Documentation Updates:

Created comprehensive docs/REACT.md documentation
Updated README.md to highlight the new feature
Added ReAct information to docs/FEATURES.md
Updated documentation index in docs/README.md
Code Implementation:

Added react_mode flag to the Agent struct
Implemented generate_reasoning() function
Integrated ReAct logic into chat execution methods
Added builder method for enabling ReAct
Examples and Tests:

Created examples/react_agent.rs with complete ReAct demonstration
Added comprehensive test suite in tests/react_tests.rs
Updated integration tests with ReAct-specific tests
The ReAct feature allows developers to create agents that think before they act, which is particularly useful for complex multi-step tasks requiring planning and coordination, while maintaining the existing functionality for simpler use cases.