feat: add Task Result API support with example and unit tests

[TanyaSingh369-svg]

Summary

Adds support for the Task Result API in the Python SDK.

This enables retrieving run task results via task_result_id, including full model representation, resource integration, and example usage.

Changes

• Added TaskResult model with all relevant fields and enums
• Added TaskResults resource with read method
• Updated client to expose task_results API
• Updated task stage model to include task result relationship
• Added example (examples/task_result.py) demonstrating usage with task_result_id
• Added unit tests for task result functionality

Testing

• Verified using real task_result_id values retrieved via:
  GET /runs/{run_id}/task-stages
• Confirmed correct parsing of API response into model
• Unit tests added to validate functionality

Validation

Unit Test

python -m pytest tests/units/test_task_results.py -v

Result:
All tests passed successfully

Example Execution

export TFE_TASK_RESULT_ID=<task_result_id>
PYTHONPATH=. python examples/task_result.py

Result:
- Successfully retrieved and displayed Task Result from API
- Verified correct parsing of response into SDK model

[isivaselvan]

task stage relation was not mapped to the read output and the response shows None