Refactor drag handling and update tests

- Renamed `initiate_drag` to `handle_drag` in MainWindow and updated related tests.
- Improved drag handling logic to utilize a bridge for starting file drags.
- Updated `_on_drag_started` and `_on_drag_failed` methods to match new signatures.
- Modified test cases to reflect changes in drag handling and assertions.

Enhance path validation and logging

- Updated `PathValidator` to log warnings for nonexistent roots instead of raising errors.
- Adjusted tests to verify the new behavior of skipping nonexistent roots.

Update web application UI and functionality

- Changed displayed text for drag items to reflect local paths and Azure Blob Storage URLs.
- Added debug logging for drag operations in the web application.
- Improved instructions for testing drag and drop functionality.

Add configuration documentation and example files

- Created `CONFIG_README.md` to provide detailed configuration instructions for WebDrop Bridge.
- Added `config.example.json` and `config_test.json` for reference and testing purposes.

Implement URL conversion logic

- Introduced `URLConverter` class to handle conversion of Azure Blob Storage URLs to local paths.
- Added unit tests for URL conversion to ensure correct functionality.

Develop download interceptor script

- Created `download_interceptor.js` to intercept download-related actions in the web application.
- Implemented logging for fetch calls, XMLHttpRequests, and Blob URL creations.

Add download test page and related tests

- Created `test_download.html` for testing various download scenarios.
- Implemented `test_download.py` to verify download path resolution and file construction.
- Added `test_url_mappings.py` to ensure URL mappings are loaded correctly.

Add unit tests for URL converter

- Created `test_url_converter.py` to validate URL conversion logic and mapping behavior.

tests/unit/test_main_window.py

@@ -231,10 +231,12 @@ class TestMainWindowDragIntegration:
         assert window.drag_interceptor.drag_started is not None
         assert window.drag_interceptor.drag_failed is not None
 
-    def test_initiate_drag_delegates_to_interceptor(
+    def test_handle_drag_delegates_to_interceptor(
         self, qtbot, sample_config, tmp_path
     ):
-        """Test initiate_drag method delegates to interceptor."""
+        """Test drag handling delegates to interceptor."""
+        from PySide6.QtCore import QCoreApplication
+        
         window = MainWindow(sample_config)
         qtbot.addWidget(window)
 
@@ -243,29 +245,32 @@ class TestMainWindowDragIntegration:
         test_file.write_text("test")
 
         with patch.object(
-            window.drag_interceptor, "initiate_drag"
+            window.drag_interceptor, "handle_drag"
         ) as mock_drag:
             mock_drag.return_value = True
-            result = window.initiate_drag([str(test_file)])
+            # Call through bridge
+            window._drag_bridge.start_file_drag(str(test_file))
+            
+            # Process deferred QTimer.singleShot(0, ...) call
+            QCoreApplication.processEvents()
 
-            mock_drag.assert_called_once_with([str(test_file)])
-            assert result is True
+            mock_drag.assert_called_once_with(str(test_file))
 
     def test_on_drag_started_called(self, qtbot, sample_config):
         """Test _on_drag_started handler can be called."""
         window = MainWindow(sample_config)
         qtbot.addWidget(window)
 
-        # Should not raise
-        window._on_drag_started(["/some/path"])
+        # Should not raise - new signature has source and local_path
+        window._on_drag_started("https://example.com/file.png", "/local/path/file.png")
 
     def test_on_drag_failed_called(self, qtbot, sample_config):
         """Test _on_drag_failed handler can be called."""
         window = MainWindow(sample_config)
         qtbot.addWidget(window)
 
-        # Should not raise
-        window._on_drag_failed("Test error message")
+        # Should not raise - new signature has source and error
+        window._on_drag_failed("https://example.com/file.png", "Test error message")
 
 
 class TestMainWindowURLWhitelist: