feat: use image concurrency for outfit directories

tests/test_outfit_batch.py

@@ -91,15 +91,17 @@ class TestOutfitBatchRunner(unittest.TestCase):
         self.assertEqual(summary.success_count, 1)
         self.assertEqual(summary.results[0].attempts, 2)
 
-    def test_concurrency_runs_more_than_one_task_at_once(self):
+    def test_concurrency_option_does_not_parallelize_excel_rows(self):
         from core.outfit_batch import OutfitBatchOptions, OutfitBatchRunner
 
         active = [0]
         max_active = [0]
+        started = []
         lock = threading.Lock()
 
         def generate(task):
             with lock:
+                started.append(task.row_index)
                 active[0] += 1
                 max_active[0] = max(max_active[0], active[0])
             time.sleep(0.05)
@@ -116,7 +118,8 @@ class TestOutfitBatchRunner(unittest.TestCase):
         summary = runner.run()
 
         self.assertEqual(summary.success_count, 4)
-        self.assertGreaterEqual(max_active[0], 2)
+        self.assertEqual(max_active[0], 1)
+        self.assertEqual(started, [2, 3, 4, 5])
 
     def test_task_cooldown_is_applied(self):
         from core.outfit_batch import OutfitBatchOptions, OutfitBatchRunner