fix: unnecessary foreign key in Entity::$original

[michalsn]

Description
This PR fixes a bug where the entity is not fully synchronized.

Fixes #19

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[neznaika0]

See also HasRelations::getDataForRelationByIds(), HasRelations::getDataForRelationById().

example, students have cources.

protected attributes -> array (6) [  // <<<
            'id' => string (1) "1"
            'firstname' => string (3) "Joe"
            'lastname' => string (5) "Smith"
            'created_at' => string (19) "2025-10-07 16:43:54"
            'updated_at' => string (19) "2025-10-07 16:43:54"
            'courses' => array (3) [
                0 => Tests\Support\Entities\Course#1178 (9) (
       ...

        protected original -> array (5) [ // <<<
            'id' => string (1) "1"
            'firstname' => string (3) "Joe"
            'lastname' => string (5) "Smith"
            'created_at' => string (19) "2025-10-07 16:43:54"
            'updated_at' => string (19) "2025-10-07 16:43:54"
        ]

You also need to synchronize for `with()'. At least for find*, we get a new object simply by modifying it before using it.

While I was writing a comment... This may be a mistake for lazy loading.
Case:

• Requested objects without courses
• The student has been changed, there are no courses
• We lazily load courses and synchronized them along with the changes.
  Seems like you just need to update the $original['cources'] here?

[michalsn]

Seems like a can of worms. Honestly, I never use $entity->hasChanged() or pay much attention to that status. I don't have a better idea for handling it right now, so I'll just leave it as is for now.

[neznaika0]

I'll try to find a solution. Yes, I've also used hasChanged() a 2-3 of times. But we are trying to create a solution for many people.

Fix solves half of the problem. You can leave it as a temporary solution.