feat: implement migration support for existing LangGraph projects

[swj9707]

Checked other resources

• This is a feature request/enhancement for Act Operator CLI, not a bug report.
• I added a clear, concise, and descriptive title for the proposal.
• I searched existing issues/PRs and did not find a duplicate.

💪 Ownership Declaration (Optional)

• 🙋 Hand-raise: I want to implement this feature myself
• 🤝 Collaboration Welcome: I want to work on this with others
• 💡 Idea Only: Proposing for someone else to implement

💡 What do you want?

A colleague working on a LangGraph project expressed a need to migrate their workflow to Act Operator.
Currently, there is no automated or structured way to handle this transition.

💻 Example CLI or Code (Optional)

No response

📸 Screenshots or Output (Optional)

No response