[AI Bundle][OpenAI] Register normalizer contract

[glengemann]

Q	A
Bug fix?	yes
New feature?	no
Docs?	no
Issues	Fix #...
License	MIT

Christopher, I think we need to register the normalizer contract so that it’s available when using the Symfony bundle.

[Copilot]

Pull Request Overview

This PR updates the OpenAI contract registration in the Symfony AI bundle to use the proper factory method instead of manually configuring the AudioNormalizer dependency.

• Replaces manual contract configuration with factory-based registration
• Switches from parent service pattern to direct factory instantiation
• Updates import to use OpenAiContract class

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[chr-hertel]

Guillermo, i think you are right :)

[chr-hertel]

Thank you @glengemann.