feat: implement Tone.js for professional audio transmit and listen

- Replace AudioWorkletNode with Tone.UserMedia for microphone capture
- Use Tone.Analyser for waveform analysis and Tone.Meter for level detection
- Implement proper stereo audio capture with real-time PCM transmission
- Use Tone.context for audio playback with proper buffer handling
- Add Tone.js CDN to HTML template
- Convert dashboard.js to ES module for Tone.js import
- Improve audio quality and reliability with battle-tested library

package.json

@@ -34,6 +34,7 @@
     "react": "^19.2.6",
     "react-dom": "^19.2.6",
     "sodium-native": "^4.3.2",
+    "tone": "^15.1.22",
     "ws": "^8.20.1",
     "zod": "^4.4.3"
   },