fix:Fix Null Name Constraint Violation testimonial

[nyainda]

Description

Fix the 500 Internal Server Error caused by an integrity constraint violation when creating testimonials with a null name value.

Acceptance Criteria

• POST /testimonials succeeds even if user name is null
• Fallback logic uses username or "Anonymous User" when name is null
• No 500 errors occur during testimonial creation
• Tests verify the fallback behavior

Purpose

Resolves a critical bug blocking testimonial creation when user profiles lack a name, improving system reliability.

Requirements

• Update TestimonialController to handle null names
• Laravel framework with MySQL

Expected Outcome

Users can create testimonials without errors, with a fallback name displayed if their profile name is missing.

Additional Context

• Current error screenshot:
• Priority: High - Blocks core functionality