Fix subagent params alias dispatch

[RED-ROSE515]

Summary

Fixes #355.

Sub-agent action dispatch now accepts params as an alias for parameters.
Some LLM outputs mirror the compact action schema key params, which previously caused the runner to drop the payload before calling sub_task_end.
As a result, sub_task_end received only _session_id and failed with Invalid status.

Changes

• Added parameter extraction helper in SubAgentRunner
• Preserves existing parameters behavior and gives it precedence over params
• Added regression tests for:
  • params alias dispatch
  • parameters precedence when both keys are present

Verification

• Direct full reproduction passed
• Focused regression functions passed
• python -m compileall app\subagent\runner.py tests\test_subagent_runner.py passed

[RED-ROSE515]

Hello @zfoong , @ahmad-ajmal , @korivi-CraftOS .
Please check this PR and let me know if it's not working on your side.
Thanks.

[zfoong]

Is it possible to fix the output format and make sure the LLM does not return a fault format, rather than having an ad hoc parser to handle special cases like this? Code will be harder to manage with bandaid solution like this. But I would like to keep this PR open and observe if this happens too frequently. If yes, perhaps it is good to keep this here.