feat: implement full breadcrumb path navigation in Files tab

- Add breadcrumbPath array to app state for tracking folder hierarchy
- Rewrite updateBreadcrumb() to render full path: Home > folder > subfolder
- Each breadcrumb segment is clickable to navigate back to that level
- Current folder shown in bold (non-clickable), parent folders as links
- Reset breadcrumb path on tab switch, home navigation, and initial load
- Update navigateFolder/selectFolder to push to breadcrumb path
- Enhanced breadcrumb CSS with hover effects and dark mode support

static/js/app/authSession.js

@@ -205,17 +205,20 @@ async function resolveHomeFolder() {
             app.userHomeFolderId = home.id;
             app.userHomeFolderName = home.name;
             app.currentPath = home.id;
-            window.ui.updateBreadcrumb(home.name);
+            app.breadcrumbPath = [];
+            window.ui.updateBreadcrumb();
             console.log(`Home folder resolved: ${home.name} (${home.id})`);
         } else {
             console.warn('No root folders found for user');
             app.currentPath = '';
-            window.ui.updateBreadcrumb('');
+            app.breadcrumbPath = [];
+            window.ui.updateBreadcrumb();
         }
     } catch (error) {
         console.error('Error resolving home folder:', error);
         app.currentPath = '';
-        window.ui.updateBreadcrumb('');
+        app.breadcrumbPath = [];
+        window.ui.updateBreadcrumb();
     }
 }