Add helper functions for output_validator

[Z-M-Huang]

Sometimes, when output_validator is attached to the tools list, LLM may just return end turn reason as stop instead of calling the output_validator. In this case, the next reasonable interaction would return the prompt to LLM instruct it to use output_validator to get the result.
We should create a helper function to handle that interaction to check if the turn used the output_validator properly

[github-actions[bot]]

GitVibe Validation

Status: completed
Next state: ready-for-implementation

Discussion #3 is authorized for validation by the gvi:validating label and is ready for implementation. All 3 configured role reviewers completed successfully, and repository inspection confirms the output-validator tool exists while the requested helper utilities are not present.

Next Action

Continue with ready-for-implementation.

Result

Full details are in the workflow run summary.
Workflow run: https://github.com/markhuangai/agentool/actions/runs/26418132368

[github-actions[bot]]

GitVibe Implementation Issues Running

GitVibe is running the materialize stage for discussion #3.

Workflow run: https://github.com/markhuangai/agentool/actions/runs/26429217879

[github-actions[bot]]

GitVibe created implementation issue #4: #4.