- Add XCEngine音频模块架构设计.md - Design audio system following Unity-style architecture - Include AudioSourceComponent, AudioListenerComponent, AudioClip, AudioMixer - Document DSP effect system (FFT, Reverb, EQ, Compressor) - Document 3D spatial audio with HRTF support - Define IAudioBackend abstraction layer with WASAPI/OpenAL backends - Outline 5-phase implementation priorities