Replace alert with notification utilities and refactor canvas creation

Replaces all uses of alert() with showErrorNotification or showSuccessNotification for improved user experience and consistency. Refactors canvas creation to use the createCanvas utility function across multiple files, reducing code duplication and improving maintainability. Also updates layer ID generation to use generateUUID.

src/CanvasSelection.ts

@@ -1,4 +1,5 @@
 import { createModuleLogger } from "./utils/LoggerUtils.js";
+import { generateUUID } from "./utils/CommonUtils.js";
 
 const log = createModuleLogger('CanvasSelection');
 
@@ -26,7 +27,7 @@ export class CanvasSelection {
         sortedLayers.forEach(layer => {
             const newLayer = {
                 ...layer,
-                id: `layer_${+new Date()}_${Math.random().toString(36).substr(2, 9)}`,
+                id: generateUUID(),
                 zIndex: this.canvas.layers.length, // Nowa warstwa zawsze na wierzchu
             };
             this.canvas.layers.push(newLayer);