Fix documentation inconsistency in UserContext example

Problem

The documentation in docs/agents.md & docs/ja/agents.md contained an inconsistency where the dynamic_instructions function referenced context.context.name, but the UserContext dataclass only defined uid and is_pro_user fields. This would cause a runtime AttributeError when users tried to follow the example.

Solution

• Added the missing name: str field to the UserContext dataclass to match what the dynamic_instructions function expects.

Changes Made

• Added name: str field to the UserContext dataclass in the Context section
• Maintained consistency between the dataclass definition and the dynamic instructions example
• Fixed formatting issues in related files

Testing

✅ Code formatting passes (make format-check)
✅ Documentation example is now consistent and functional
✅ No runtime errors when following the example
✅ Verified locally: Ran make serve-docs and confirmed the documentation renders correctly with the fix(make serve-docs)

Issue number

Fixes #1262