backuptask: track copy and upload statistics

src/progress-stream.js

@@ -22,8 +22,8 @@ class ProgressStream extends TransformStream {
     }
 
     stats() {
-        const totalMsecs = Date.now() - this.#startTime;
-        return { startTime: this.#startTime, totalMsecs, transferred: this.#transferred };
+        const duration = Date.now() - this.#startTime;
+        return { startTime: this.#startTime, duration, transferred: this.#transferred };
     }
 
     _start() {