Add useTimer hook for managing a timer with start, stop, and formatting functionality

src/hooks/useTimer.ts

@@ -0,0 +1,29 @@
+import { useState, useRef } from "react";
+
+export function useTimer() {
+  const [seconds, setSeconds] = useState(0);
+  const intervalRef = useRef<ReturnType<typeof setInterval> | null>(null);
+
+  function startTimer() {
+    setSeconds(0);
+    intervalRef.current = setInterval(() => {
+      setSeconds((prev) => prev + 1);
+    }, 1000);
+  }
+
+  function stopTimer() {
+    if (intervalRef.current) {
+      clearInterval(intervalRef.current);
+    }
+    setSeconds(0);
+  }
+
+  function formatTime(seconds: number) {
+    const hrs = Math.floor(seconds / 3600);
+    const mins = Math.floor((seconds % 3600) / 60);
+    const secs = seconds % 60;
+    return `${String(hrs).padStart(2, "0")}:${String(mins).padStart(2, "0")}:${String(secs).padStart(2, "0")}`;
+  }
+
+  return { timer: formatTime(seconds), startTimer, stopTimer };
+}