Ensure Fallback Name Handling in input_guardrail

Problem

The input_guardrail logic previously allowed the name attribute to be None if not explicitly provided. This caused issues in downstream systems such as logging, tracing, or serialization that expect a valid string name.

Changes

Introduced fallback logic to assign a default name if name is None.
Guarantees that all function metadata includes a valid string name.
Prevents unpredictable behavior or runtime errors in downstream processes.

Impact

Improves system robustness and fault tolerance.
Ensures consistent behavior in tools relying on function names.
No breaking changes introduced.