✨(frontend) add date formatting utility function

Create reusable utility function to format dates into specified patterns.
Provides consistent date formatting across the application.

src/frontend/src/utils/formatDate.ts

@@ -0,0 +1,29 @@
+export function formatDate(
+  date: Date | string | number,
+  format: string = 'YYYY-MM-DD'
+): string {
+  const dateObj = date instanceof Date ? date : new Date(date)
+
+  if (isNaN(dateObj.getTime())) {
+    return 'Invalid Date'
+  }
+
+  const year = dateObj.getFullYear()
+  const month = dateObj.getMonth() + 1 // getMonth() returns 0-11
+  const day = dateObj.getDate()
+  const hours = dateObj.getHours()
+  const minutes = dateObj.getMinutes()
+  const seconds = dateObj.getSeconds()
+
+  const pad = (num: number): string => String(num).padStart(2, '0')
+
+  let result = format
+  result = result.replace(/YYYY/g, year.toString())
+  result = result.replace(/MM/g, pad(month))
+  result = result.replace(/DD/g, pad(day))
+  result = result.replace(/HH/g, pad(hours))
+  result = result.replace(/mm/g, pad(minutes))
+  result = result.replace(/ss/g, pad(seconds))
+
+  return result
+}