The system message now clearly states that the <tool_call> XML tags MUST
be literally written in the response, not just described. Includes examples
of CORRECT vs WRONG usage to help smaller models understand.
- Add onToken callback option to IDualAgentOptions interface
- Add onToken property and setOnToken method to DriverAgent
- Wire up streaming in startTask and continueWithMessage methods
- Pass source identifier ('driver'/'guardian') to onToken callback
