Fix dependency loading

Changes

• Fix missing faraday dependency
• Update dependency loading in dependable concern

Support Ollama and OpenRouter

Changes

• Add Regent::LLM::Ollama provider to use local LLMs
• Add Regent::LLM::OpenRouter provider
• Allow defining tool functions on the agent itself:

class MyAgent < Regent::Agent
  tool :my_tool, "Tool description"
  
  def  my_tool
    # call tool
  end
end

Improve tool calling

• Update ReAct agent system prompt to return Action in JSON format
• Allow Tool to accept multiple arguments
• Extract logic potential common for different engines into Regent::Engine::Base
• Update LLM interface:
  • Add strict_mode optional argument
• Update Agent interface:
  • execute method renamed to run
  • llm argument renamed to model
  • Add engine optional argument for future use with different engine

Full Changelog: v0.3.1...v0.3.2

Fix logger and improve test coverage

Full Changelog: v0.3.0...v0.3.1

Implement LLM class and update interfaces

• LLMs can now be instantiated with Regent::LLM.new("gpt-4o-mini")
• Agent supports purpose Regent::Agent.new("You are a weather assistant", llm: llm)

Basic agent version

v0.2.0

Update README.md