This commit adds validation to detect and reject async methods in crew
decorators (@agent, @task, @crew, @llm, @tool, @callback, @cache_handler,
@before_kickoff, @after_kickoff).
Previously, decorating async methods would silently fail at runtime with
confusing errors like "'coroutine' object has no attribute 'name'".
Now, a clear TypeError is raised at decoration time with:
- The specific decorator name that doesn't support async
- The method name that was incorrectly defined as async
- Helpful suggestions for workarounds
Fixes#3988
Co-Authored-By: João <joao@crewai.com>
