feat(data-schema): add Schema.transform()

[mcansh]

Add Schema.transform() to the data-schema chainable API so schemas can map a successfully validated output value into a new output value and type.

let Event = object({
  id: string(),
  createdAt: string()
    .refine((value) => !Number.isNaN(Date.parse(value)), 'Expected valid date')
    .transform((value) => new Date(value)),
})

• Runs transformers after the underlying schema succeeds and leaves validation failures untouched.
• Preserves the original input type while changing the schema output type.
• Documents usage and adds a release note for @remix-run/data-schema.

[Copilot]

Pull request overview

This PR adds a Schema.transform(...) modifier to data-schema so consumers can map a successfully-validated output value into a new output type, and introduces tests covering transform behavior and chaining with other modifiers.

Changes:

• Added a new transform method to the Schema chainable API and its createSchema implementation.
• Added tests for transform, including chaining order with refine.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
packages/data-schema/src/lib/schema.ts	Adds Schema.transform typing + implementation to map validated output to a new output type.
packages/data-schema/src/lib/schema.test.ts	Adds test cases validating transform behavior and chaining with existing modifiers.

[mjackson]

thanks for the PR, @mcansh! 💪