feat: implement audio object definitions and refactor audio system

- Add AudioObjectDefinitions.cs with name-to-ID mappings and ambiguity detection
- Update AudioSystem.cs to support Play(uint) and deprecated Play(string) with warnings
- Rename PitchStepManager to PitchStepResolver and update all references
- Refactor generated code to use 'this.' prefix and foreach loops
- Remove TestEnum from audio enums and IDs
- Update SampleScene.unity to use new AudioSystem namespace and rain sound parameter
- Optimize binary serialization in generated audio classes

Assets/Scripts/OCES/Audio/Generated/AudioObjectDefinitions.cs.meta

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