fix: column view navigation and duplicate app instance

- Fix duplicate tsview-app rendering by checking if element already exists in HTML
- Fix column navigation to expand horizontally instead of resetting
- Remove navigate event dispatch from column folder selection to preserve column state

ts_web/index.ts

@@ -13,9 +13,11 @@ const initApp = async () => {
   // Wait for custom elements to be defined
   await customElements.whenDefined('tsview-app');
 
-  // Create and mount the app
-  const app = document.createElement('tsview-app');
-  document.body.appendChild(app);
+  // Only create the app element if it doesn't already exist in HTML
+  if (!document.querySelector('tsview-app')) {
+    const app = document.createElement('tsview-app');
+    document.body.appendChild(app);
+  }
 
   console.log('TsView UI ready');
 };