Sine wave audio test

# Sine wave audio test This world exists to verify that audio playback works. On load, the **SineSpeaker** entity (the cyan sphere) plays a looping **440 Hz sine wave** (`audio/sine.wav`, an exact 2 s / 880-cycle loop so it repeats seamlessly) through the engine's Kira mixer on the `music` channel. ## How to test - Open the world — the tone autoplays. Enter **Play** mode if your client gates audio to play mode. - You should hear a steady, clean 440 Hz tone with no clicks at the loop boundary. ## How it's built - `audio/sine.wav` — generated 16-bit mono PCM sine, 44.1 kHz, 0.6 amplitude. - `scenes/main.scene` — the `SineSpeaker` entity carries a `Model` (sphere) plus an `Audio` component (`url = audio/sine.wav`, `looping = true`, `autoplay = true`, `sourceType = Music`).