Fix double-serialization of binary UUIDs in BelongsToMany relationships

[tlsqr]

Summary

• Fix "Incorrect UUID version" error when using BelongsToMany pivot operations with binary UUID keys
• Add binary detection check to prevent double-serialization of already-serialized values

Problem

When using BelongsToMany relationships with binary UUID primary keys (via mutators), pivot operations like updateExistingPivot(), sync(), attach(), and detach() could fail with:

Ramsey\Uuid\Exception\InvalidArgumentException: Incorrect UUID version

This occurs because parseId() and parseIds() attempt to serialize values that are already in binary format. The existing cache check (in_array($value, $this->mutated_values)) only catches values serialized within the same instance, not binary values from other sources.

Root Cause

This bug was introduced with the upgrade to ramsey/uuid 4.x (Laravel 7+). Version 4.x is stricter about UUID validation and throws an exception when attempting to parse binary data as a UUID string.

Solution

Added a ctype_print() check before serialization to detect already-binary values:

• UUID strings contain only printable characters (hex + hyphens) → ctype_print() returns true
• Binary UUIDs (16 bytes) contain non-printable bytes → ctype_print() returns false