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.

src/webdrop_bridge/ui/download_interceptor.js

@@ -0,0 +1,72 @@
+// Download Interceptor Script
+// Intercepts JavaScript-based downloads (fetch, XMLHttpRequest, Blob URLs)
+
+(function() {
+    'use strict';
+    
+    console.log('🔍 Download interceptor script loaded');
+    
+    // Intercept fetch() calls
+    const originalFetch = window.fetch;
+    window.fetch = function(...args) {
+        const url = args[0];
+        console.log('🌐 Fetch called:', url);
+        
+        // Check if this looks like a download
+        if (typeof url === 'string') {
+            const urlLower = url.toLowerCase();
+            const downloadPatterns = [
+                '/download', '/export', '/file', 
+                '.pdf', '.zip', '.xlsx', '.docx', 
+                'attachment', 'content-disposition'
+            ];
+            
+            if (downloadPatterns.some(pattern => urlLower.includes(pattern))) {
+                console.log('📥 Potential download detected via fetch:', url);
+            }
+        }
+        
+        return originalFetch.apply(this, args);
+    };
+    
+    // Intercept XMLHttpRequest
+    const originalXHROpen = XMLHttpRequest.prototype.open;
+    XMLHttpRequest.prototype.open = function(method, url, ...rest) {
+        console.log('🌐 XHR opened:', method, url);
+        this._url = url;
+        return originalXHROpen.apply(this, [method, url, ...rest]);
+    };
+    
+    const originalXHRSend = XMLHttpRequest.prototype.send;
+    XMLHttpRequest.prototype.send = function(...args) {
+        console.log('📤 XHR send:', this._url);
+        return originalXHRSend.apply(this, args);
+    };
+    
+    // Intercept Blob URL creation
+    const originalCreateObjectURL = URL.createObjectURL;
+    URL.createObjectURL = function(blob) {
+        console.log('🔗 Blob URL created, size:', blob.size, 'type:', blob.type);
+        return originalCreateObjectURL.apply(this, arguments);
+    };
+    
+    // Intercept anchor clicks that might be downloads
+    document.addEventListener('click', function(e) {
+        const target = e.target.closest('a');
+        if (target && target.href) {
+            const href = target.href;
+            const download = target.getAttribute('download');
+            
+            if (download !== null) {
+                console.log('📥 Download link clicked:', href, 'filename:', download);
+            }
+            
+            // Check for blob URLs
+            if (href.startsWith('blob:')) {
+                console.log('📦 Blob download link clicked:', href);
+            }
+        }
+    }, true);
+    
+    console.log('✅ Download interceptor active');
+})();