feat: added isValidUnixTimestamp

ts/session/utils/Timestamps.ts

@@ -0,0 +1,16 @@
+/**
+ * Checks if the given value is a valid Unix timestamp.
+ * @param value timestamp in milliseconds
+ */
+export function isValidUnixTimestamp(value: number): boolean {
+  // The Unix timestamp is a way to track time as a running total of seconds.
+  // It counts the number of seconds since January 1, 1970 (UTC).
+  // Hence, it should be a non-negative number.
+  if (typeof value !== 'number' || value < 0) {
+    return false;
+  }
+
+  // Convert the Unix timestamp to a Date object and check if it's valid.
+  const date = new Date(value * 1000);
+  return date instanceof Date && !Number.isNaN(date);
+}