feat: add StorageManager, VisualizationManager, UIManager, EditorManager, and update PanelResizer for improved snippet handling and visualization

src/VisualizationManager.js

@@ -0,0 +1,22 @@
+export class VisualizationManager {
+    constructor(containerId = 'vis') {
+        this.containerId = containerId;
+    }
+
+    async updateVisualization(spec) {
+        try {
+            const parsedSpec = typeof spec === 'string' ? JSON.parse(spec) : spec;
+            parsedSpec.width = parsedSpec.width || 'container';
+            parsedSpec.height = parsedSpec.height || 'container';
+            
+            await vegaEmbed(`#${this.containerId}`, parsedSpec, {
+                actions: true,
+                theme: 'light'
+            });
+        } catch (err) {
+            console.error('Error rendering visualization:', err);
+            document.getElementById(this.containerId).innerHTML =
+                `<div style="color: red; padding: 1rem;">Error rendering visualization: ${err.message}</div>`;
+        }
+    }
+}