feat: add Tone Generator tool with precise audio controls and wave selection

README.md

@@ -40,6 +40,13 @@ Scan QR codes directly from your camera or device.
 - **History:** Keeps a log of scanned codes with options to copy or download as JSON.
 - **Responsive:** Fullscreen mode for immersive scanning experience.
 
+### 🎵 Tone Generator
+Generate precise audio frequencies directly in the browser.
+- **Customizable:** Slide from 20 Hz to 20,000 Hz or type exact values.
+- **Waveforms:** Choose between Sine, Square, Sawtooth, and Triangle waves.
+- **Presets:** Quick access to common frequencies like 440 Hz (A4) and 528 Hz.
+- **Safe:** Smooth volume ramping to protect against audio clicking.
+
 ---
 
 ## Chrome Extension 🧩