Refactor: Defer folder creation to download time

- Remove folder creation from add_series endpoint
- Add folder creation to download() method in SeriesApp
- Maintain database persistence and targeted scanning
- Update tests to use tmp_path fixtures
- All add_series and download tests passing (13/13)

tests/unit/test_series_app.py

@@ -107,10 +107,14 @@ class TestSeriesAppDownload:
     @patch('src.core.SeriesApp.SerieScanner')
     @patch('src.core.SeriesApp.SerieList')
     async def test_download_success(
-        self, mock_serie_list, mock_scanner, mock_loaders
+        self, mock_serie_list, mock_scanner, mock_loaders, tmp_path
     ):
         """Test successful download."""
-        test_dir = "/test/anime"
+        test_dir = str(tmp_path / "anime")
+        # Create the test directory
+        import os
+        os.makedirs(test_dir, exist_ok=True)
+        
         app = SeriesApp(test_dir)
         
         # Mock the events to prevent NoneType errors
@@ -130,16 +134,24 @@ class TestSeriesAppDownload:
         # Verify result
         assert result is True
         app.loader.download.assert_called_once()
+        
+        # Verify folder was created
+        folder_path = os.path.join(test_dir, "anime_folder")
+        assert os.path.exists(folder_path)
 
     @pytest.mark.asyncio
     @patch('src.core.SeriesApp.Loaders')
     @patch('src.core.SeriesApp.SerieScanner')
     @patch('src.core.SeriesApp.SerieList')
     async def test_download_with_progress_callback(
-        self, mock_serie_list, mock_scanner, mock_loaders
+        self, mock_serie_list, mock_scanner, mock_loaders, tmp_path
     ):
         """Test download with progress callback."""
-        test_dir = "/test/anime"
+        test_dir = str(tmp_path / "anime")
+        # Create the test directory
+        import os
+        os.makedirs(test_dir, exist_ok=True)
+        
         app = SeriesApp(test_dir)
         
         # Mock the events
@@ -172,10 +184,14 @@ class TestSeriesAppDownload:
     @patch('src.core.SeriesApp.SerieScanner')
     @patch('src.core.SeriesApp.SerieList')
     async def test_download_cancellation(
-        self, mock_serie_list, mock_scanner, mock_loaders
+        self, mock_serie_list, mock_scanner, mock_loaders, tmp_path
     ):
         """Test download cancellation during operation."""
-        test_dir = "/test/anime"
+        test_dir = str(tmp_path / "anime")
+        # Create the test directory
+        import os
+        os.makedirs(test_dir, exist_ok=True)
+        
         app = SeriesApp(test_dir)
         
         # Mock the events