Add drag & drop script variants and enhanced debugging tools

- Introduced multiple JavaScript scripts for handling drag & drop functionality:
  - `bridge_script.js`: Original implementation with popup prevention.
  - `bridge_script_debug.js`: Debug version with extensive logging for troubleshooting.
  - `bridge_script_v2.js`: Enhanced version extending DataTransfer for better integration.
  - `bridge_script_hybrid.js`: Hybrid approach allowing parallel native file drag.
  - `bridge_script_drop_intercept.js`: Intercepts drop events for custom handling.
  - `bridge_script_intercept.js`: Prevents browser drag for ALT+drag, using Qt for file drag.

- Added detailed documentation in `SCRIPT_VARIANTS.md` outlining usage, status, and recommended workflows for each script.
- Implemented logging features to capture drag events, DataTransfer modifications, and network requests for better debugging.
- Enhanced DataTransfer handling to support Windows-specific file formats and improve user experience during drag & drop operations.

src/webdrop_bridge/ui/bridge_script_intercept.js

@@ -0,0 +1,165 @@
+// WebDrop Bridge - Intercept Version
+// Prevents browser drag for ALT+drag, hands off to Qt for file drag
+
+(function() {
+  if (window.__webdrop_intercept_injected) return;
+  window.__webdrop_intercept_injected = true;
+
+  // Intercept mode enabled
+  var INTERCEPT_ENABLED = true;
+
+  console.log('%c[WebDrop Intercept] Script loaded - INTERCEPT_ENABLED=' + INTERCEPT_ENABLED, 'background: #2196F3; color: white; font-weight: bold; padding: 4px 8px;');
+  
+  var currentDragUrl = null;
+  var angularDragHandlers = [];
+  var originalAddEventListener = EventTarget.prototype.addEventListener;
+  var listenerPatchActive = true;
+  
+  // Capture Authorization token from XHR requests
+  window.capturedAuthToken = null;
+  var originalXHRSetRequestHeader = XMLHttpRequest.prototype.setRequestHeader;
+  XMLHttpRequest.prototype.setRequestHeader = function(header, value) {
+    if (header === 'Authorization' && value.startsWith('Bearer ')) {
+      window.capturedAuthToken = value;
+      console.log('[Intercept] Captured auth token');
+    }
+    return originalXHRSetRequestHeader.apply(this, arguments);
+  };
+  
+  // ============================================================================
+  // PART 1: Intercept Angular's dragstart listener registration
+  // ============================================================================
+  
+  EventTarget.prototype.addEventListener = function(type, listener, options) {
+    if (listenerPatchActive && type === 'dragstart' && listener) {
+      // Store Angular's dragstart handler instead of registering it
+      console.log('[Intercept] Storing Angular dragstart listener for', this.tagName || this.constructor.name);
+      angularDragHandlers.push({
+        target: this,
+        listener: listener,
+        options: options
+      });
+      return; // Don't actually register it yet
+    }
+    // All other events: use original
+    return originalAddEventListener.call(this, type, listener, options);
+  };
+  
+  // ============================================================================
+  // PART 2: Intercept DataTransfer.setData to capture URL
+  // ============================================================================
+  
+  var originalSetData = DataTransfer.prototype.setData;
+  
+  DataTransfer.prototype.setData = function(format, data) {
+    if (format === 'text/plain' || format === 'text/uri-list') {
+      currentDragUrl = data;
+      console.log('%c[Intercept] Captured URL:', 'color: #4CAF50; font-weight: bold;', data.substring(0, 80));
+    }
+    return originalSetData.call(this, format, data);
+  };
+  
+  console.log('[Intercept] DataTransfer.setData patched ✓');
+  
+  // ============================================================================
+  // PART 3: Install OUR dragstart handler in capture phase
+  // ============================================================================
+  
+  setTimeout(function() {
+    console.log('[Intercept] Installing dragstart handler, have', angularDragHandlers.length, 'Angular handlers');
+    
+    // Stop intercepting addEventListener
+    listenerPatchActive = false;
+    
+    // Register OUR handler in capture phase
+    originalAddEventListener.call(document, 'dragstart', function(e) {
+      currentDragUrl = null; // Reset
+      
+      console.log('%c[Intercept] dragstart', 'background: #FF9800; color: white; padding: 2px 6px;', 'ALT:', e.altKey);
+      
+      // Call Angular's handlers first to let them set the data
+      var handled = 0;
+      for (var i = 0; i < angularDragHandlers.length; i++) {
+        var h = angularDragHandlers[i];
+        if (h.target === document || h.target === e.target || 
+            (h.target.contains && h.target.contains(e.target))) {https://devagravitystg.file.core.windows.net/devagravitysync/anPGZszKzgKaSz1SIx2HFgduy/weiss_ORIGINAL.jpg
+          try {
+            h.listener.call(e.target, e);
+            handled++;
+          } catch(err) {
+            console.error('[Intercept] Error calling Angular handler:', err);
+          }
+        }
+      }
+      
+      console.log('[Intercept] Called', handled, 'Angular handlers, URL:', currentDragUrl ? currentDragUrl.substring(0, 60) : 'none');
+      
+      // NOW check if we should intercept
+      if (e.altKey && currentDragUrl) {
+        var isAzure = /^https?:\/\/.+\.file\.core\.windows\.net\//i.test(currentDragUrl);
+        var isZDrive = /^z:/i.test(currentDragUrl);
+        
+        if (isAzure || isZDrive) {
+          console.log('%c[Intercept] PREVENTING browser drag, using Qt', 
+                      'background: #F44336; color: white; font-weight: bold; padding: 4px 8px;');
+          
+          e.preventDefault();
+          e.stopPropagation();
+          
+          ensureChannel(function() {
+            if (window.bridge && typeof window.bridge.start_file_drag === 'function') {
+              console.log('%c[Intercept] → Qt: start_file_drag', 'color: #9C27B0; font-weight: bold;');
+              window.bridge.start_file_drag(currentDragUrl);
+            } else {
+              console.error('[Intercept] bridge.start_file_drag not available!');
+            }
+          });
+          
+          currentDragUrl = null;
+          return false;
+        }
+      }
+      
+      console.log('[Intercept] Normal drag, allowing browser');
+    }, true); // Capture phase
+    
+    console.log('[Intercept] dragstart handler installed ✓');
+  }, 1500); // Wait for Angular to register its listeners
+  
+  // ============================================================================
+  // PART 3: QWebChannel connection
+  // ============================================================================
+  
+  function ensureChannel(callback) {
+    if (window.bridge) {
+      callback();
+      return;
+    }
+    
+    if (window.QWebChannel && window.qt && window.qt.webChannelTransport) {
+      new QWebChannel(window.qt.webChannelTransport, function(channel) {
+        window.bridge = channel.objects.bridge;
+        console.log('[WebDrop Intercept] QWebChannel connected ✓');
+        callback();
+      });
+    } else {
+      console.error('[WebDrop Intercept] QWebChannel not available!');
+    }
+  }
+  
+  // Initialize channel on load
+  if (document.readyState === 'loading') {
+    document.addEventListener('DOMContentLoaded', function() {
+      ensureChannel(function() {
+        console.log('[WebDrop Intercept] Bridge ready ✓');
+      });
+    });
+  } else {
+    ensureChannel(function() {
+      console.log('[WebDrop Intercept] Bridge ready ✓');
+    });
+  }
+  
+  console.log('%c[WebDrop Intercept] Ready! ALT-drag will use Qt file drag.', 
+              'background: #4CAF50; color: white; font-weight: bold; padding: 4px 8px;');
+})();