- Add graphtool package with InvokableGraphTool and StreamableGraphTool
- Support compose.Graph, compose.Chain, and compose.Workflow via Compilable interface
- Full interrupt/resume support with checkpoint persistence
- Add 4 examples demonstrating different use cases:
- 1_chain_summarize: Document summarization with compose.Chain
- 2_graph_research: Multi-source research with compose.Graph + streaming
- 3_workflow_order: Order processing with compose.Workflow + approval
- 4_nested_interrupt: Nested interrupts (outer approval + inner risk check)
- Update InvokableApprovableTool to support nested interrupts
- Add comprehensive README documentation for package and examples
Change-Id: Ia7cceebb9e25baf6ca4db25b36eddc74eec273cb
shentong.martin