feat: add playable Wwise audio showcase

[loonghao]

Summary

• add English and Chinese Wwise audio showcase pages with three playable WAV assets
• add the approved waveform-only Wwise brand lockup and ecosystem/homepage entries
• extend site validation for localized pages, audio assets, anchors, and sitemap routes

Validation

• npm run docs:build
• source/site WAV SHA-256 hashes match
• staged sensitive-content scan passed; local Wwise project and internal commands are excluded