Signal that planning is complete and the plan is ready for implementation.

Call this tool once you have finalized the plan file and are confident it is ready. This ends your planning turn and hands control back to the user.

Call this tool:
- After you have written a complete plan to the plan file
- After you have clarified any questions with the user
- When you are confident the plan is ready for implementation

Do NOT call this tool:
- Before you have created or finalized the plan
- If you still have unanswered questions about the implementation
- If the user has indicated they want to continue planning
