feat: enhance input validation for Agent and Crew

[gilangjavier]

This PR introduces stricter input validation for core components to prevent common initialization errors.

Changes:

• BaseAgent: Added validators for role, goal, and backstory to ensure they are not empty or whitespace-only strings.
• Crew: Improved _create_task to provide a descriptive ValueError with available roles if a specified agent is not found, instead of a silent StopIteration.

These enhancements help developers catch configuration issues early during the development phase.

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Note

Low Risk
Low risk: adds stricter Pydantic validation and replaces a StopIteration with a clearer ValueError, which may surface previously-silent misconfigurations as early failures.

Overview
Adds stricter input validation for BaseAgent by rejecting empty/whitespace-only values for role, goal, and backstory at model validation time.

Improves Crew config task creation by raising a descriptive ValueError when a task references a missing agent role (including a list of available roles) instead of bubbling a StopIteration.

Includes small docstring/field description grammar fixes in Crew and Task.

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[gilangjavier]

Thanks for the review! The exception chaining issue has been fixed by adding 'from None' to the ValueError raise statement. This suppresses the noisy StopIteration traceback and provides a cleaner error message. The fix has been pushed to the branch.

[gilangjavier]

Merged latest into this branch to resolve BEHIND status (merge commit: c0bacce).

[gilangjavier]

Merged latest main into this branch to resolve BEHIND status.

Merge commit: c0bacce

[gilangjavier]

Merged main and pushed the branch update. If any required checks need to be re-triggered after the merge commit, please kick them off and I’ll address anything that comes up.