Fix ComfyUI shortcut leaks in LayerForge

Technical details:
- skip LayerForge canvas and panel shortcuts when focus is inside editable controls
- patch ComfyUI ChangeTracker undoRedo so Ctrl/Cmd+Z does not leak to graph history while LayerForge owns the shortcut context
- stop clipboard copy/cut/paste events from editable LayerForge UI from bubbling into ComfyUI node clipboard handlers
- route widget-root Ctrl/Cmd+Z, Ctrl/Cmd+Y, and Ctrl/Cmd+Shift+Z through LayerForge canvas undo and redo when the widget is active

src/CanvasInteractions.ts

@@ -163,6 +163,19 @@ export class CanvasInteractions {
         }
     }
 
+    private isEditableElement(target: EventTarget | null): boolean {
+        if (!(target instanceof HTMLElement)) {
+            return false;
+        }
+
+        if (target.isContentEditable) {
+            return true;
+        }
+
+        const editableSelector = 'input, textarea, select, [contenteditable="true"]';
+        return !!target.closest(editableSelector);
+    }
+
     setupEventListeners(): void {
         this.canvas.canvas.addEventListener('mousedown', this.onMouseDown as EventListener);
         this.canvas.canvas.addEventListener('mousemove', this.onMouseMove as EventListener);
@@ -666,6 +679,10 @@ export class CanvasInteractions {
         if (e.key === 'Shift') this.interaction.isShiftPressed = true;
         if (e.key === 'Alt') this.interaction.isAltPressed = true;
 
+        if (this.isEditableElement(e.target) || this.isEditableElement(document.activeElement)) {
+            return;
+        }
+
         // Check if canvas is focused before handling any shortcuts
         const shouldHandle = this.canvas.isMouseOver ||
             this.canvas.canvas.contains(document.activeElement) ||