do to formatters

apps/website/lib/formatters/DurationFormatter.ts

@@ -0,0 +1,24 @@
+/**
+ * DurationDisplay
+ * 
+ * Deterministic formatting for time durations.
+ */
+
+export class DurationFormatter {
+  /**
+   * Formats milliseconds as "123.45ms".
+   */
+  static formatMs(ms: number): string {
+    return `${ms.toFixed(2)}ms`;
+  }
+
+  /**
+   * Formats seconds as "M:SS.mmm".
+   * Example: 65.123 -> "1:05.123"
+   */
+  static formatSeconds(seconds: number): string {
+    const minutes = Math.floor(seconds / 60);
+    const remainingSeconds = (seconds % 60).toFixed(3);
+    return `${minutes}:${remainingSeconds.padStart(6, '0')}`;
+  }
+}