fix: add 'visual' mode to formatMode map

- Visual search mode was showing as '—' in session history
- Added 'visual': 'Visual' to the formatMode mapping

src/views/SearchView.vue

@@ -1529,6 +1529,7 @@ function formatTime(sec: number): string {
 function formatMode(mode: string | null): string {
   const map: Record<string, string> = {
     keyword: 'Keyword',
+    visual: 'Visual',
     semantic: 'Semantic',
     agent: 'Agent',
     people: 'People',