feat: implement comprehensive ADK integration for OSSA framework
- Add ADK agent type mappings (LlmAgent, WorkflowAgent, CustomAgent)
- Implement ADK state management with session.state pattern
- Create ADK tool system with capability mappings
- Add orchestration patterns (sequential, loop, conditional, parallel, coordinator, dispatcher)
- Implement MCP-ADK bridge for tool integration
- Add comprehensive examples for code review, data pipeline, and customer support
- Create detailed ADK integration documentation
- Map OSSA agent types to appropriate ADK categories
- Enable state interpolation and output_key patterns
- Support all ADK communication and delegation patterns