🐛 fix: addJobs tracks promises so batch-done waits for them

Previously addJobs() was fire-and-forget — added jobs ran as orphaned
promises. When the original batch completed, batch-done fired and
uploadManager was set to null while added jobs were still running.

Now: added job promises are tracked in _additionalPromises array.
startBatch drains this array after the original tasks complete,
ensuring batch-done only fires when ALL jobs (original + added) finish.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/upload-manager.js

@@ -136,6 +136,7 @@ class UploadManager extends EventEmitter {
     const batchId = `batch-${Date.now()}`;
     const results = new Map(); // filePath -> { name, size, results: [] }
     this._batchResults = results;
+    this._additionalPromises = []; // Track jobs added mid-batch via addJobs()
 
     for (const task of tasks) {
       const fileName = path.basename(task.file);
@@ -150,6 +151,11 @@ class UploadManager extends EventEmitter {
 
     const promises = tasks.map((task) => this._runJob(task, results, signal));
     await Promise.allSettled(promises);
+    // Wait for any jobs added mid-batch via addJobs()
+    while (this._additionalPromises.length > 0) {
+      const batch = this._additionalPromises.splice(0);
+      await Promise.allSettled(batch);
+    }
 
     this._stopStatsTimer();
     this.running = false;
@@ -703,9 +709,9 @@ class UploadManager extends EventEmitter {
         results.set(task.file, { name: fileName, size, results: [] });
       }
     }
-    // Start each new job — they'll acquire semaphores and run
+    // Start each new job and track promises so batch-done waits for them
     for (const task of tasks) {
-      this._runJob(task, results, signal);
+      this._additionalPromises.push(this._runJob(task, results, signal));
     }
   }