Split monolithic async_task_handler.go into separate handlers:
- async_task_cancel_handler.go: Handles task cancellation
- async_task_create_handler.go: Handles task creation
- async_task_progress_update_handler.go: Handles progress updates
- async_task_result_detail_handler.go: Handles result details
- async_task_result_query_handler.go: Handles result queries
- async_task_status_update_handler.go: Handles status updates
This improves code organization and maintainability by separating concerns.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
