Prerequisites checklist

• I have read the contributing guidelines.

AI acknowledgment

• I did not use AI to generate this PR.
• (If the above is not checked) I have reviewed the AI-generated content before submitting.

What did you do?

Constructed an ObjectSchema from a definitions object and then checked the original object afterward.

const definitions = {
	foo: {
		merge: "replace",
		validate: "string",
	},
};

new ObjectSchema(definitions);

What did you expect to happen?

The original definitions object should remain unchanged.

definitions.foo.merge === "replace";
definitions.foo.validate === "string";

What actually happened?

The constructor normalized the definitions in place and replaced the original string values with functions.

What is the purpose of this pull request?

This PR prevents ObjectSchema from mutating caller-provided schema definitions during construction.

What changes did you make? (Give an overview)

• Updated the constructor to normalize each definition into a local value instead of assigning normalized handlers back onto the input definitions object.
• Added a regression test.

Related Issues

Is there anything you'd like reviewers to focus on?