Implement Debug for FixedVec?

這個 Issue 沒有描述。

Find the FixedVec type definition in the source code, likely in src/lib.rs or a module like src/fixed_vec.rs. Review how the standard Debug trait is implemented for similar types in the crate. The implementation should print the elements of the FixedVec. Check for existing tests of FixedVec to understand its behavior and add a test for the Debug output.

由索引模型根據 Issue 內容生成。