Desgin doc for task search by user improvement

Issue Description

Design doc comparing and contrasting different approaches to improve task search by user

Expected Behavior

Design doc of -

• User filtering at client side
• User filtering at controller layer
• User filtering at model layer
• Migration of DB for better query control

Current Behavior

• /user allows us to search user by querying

Reproducibility

• This issue is reproducible
• This issue is not reproducible

Severity/Priority

• Critical
• High
• Medium
• Low

Additional Information

Checklist

• I have read and followed the project's code of conduct.
• I have searched for similar issues before creating this one.
• I have provided all the necessary information to understand and reproduce the issue.
• I am willing to contribute to the resolution of this issue.

The issue names the /user endpoint as the starting point; inspect its current user-search behavior and compare the client, controller, model, and database-migration approaches listed. Done means a design document that records the alternatives, trade-offs, and recommendation for improving task search by user.