Timer implemented. No working tests.

src/utils/audio.ts

@@ -0,0 +1,41 @@
+/**
+ * Plays a beep sound using the Web Audio API.
+ * @param duration Duration in milliseconds
+ * @param frequency Frequency in Hz
+ * @param volume Volume (0-1)
+ */
+export const playBeep = (duration = 200, frequency = 440, volume = 0.5) => {
+    try {
+        const AudioContext = window.AudioContext || (window as any).webkitAudioContext;
+        if (!AudioContext) return;
+
+        const ctx = new AudioContext();
+        const osc = ctx.createOscillator();
+        const gainUrl = ctx.createGain();
+
+        osc.connect(gainUrl);
+        gainUrl.connect(ctx.destination);
+
+        osc.type = 'sine';
+        osc.frequency.value = frequency;
+        gainUrl.gain.setValueAtTime(volume, ctx.currentTime);
+        gainUrl.gain.exponentialRampToValueAtTime(0.01, ctx.currentTime + duration / 1000);
+
+        osc.start(ctx.currentTime);
+        osc.stop(ctx.currentTime + duration / 1000);
+    } catch (e) {
+        console.error('Audio playback failed', e);
+    }
+};
+
+/**
+ * Plays a "Time Up" signal (3 beeps)
+ */
+export const playTimeUpSignal = async () => {
+    // 3 beeps: High-Low-High? Or just 3 Highs.
+    // Let's do 3 rapid beeps.
+    const now = Date.now();
+    playBeep(300, 880, 0.5);
+    setTimeout(() => playBeep(300, 880, 0.5), 600);
+    setTimeout(() => playBeep(600, 1200, 0.5), 1200);
+};