feat: add a user setting to toggle sidebar chat hover previews (#27632)

Co-authored-by: Tim Baek <tim@openwebui.com>

src/lib/stores/index.ts

@@ -253,6 +253,7 @@ type Settings = {
 	chatDirection?: 'LTR' | 'RTL' | 'auto';
 	ctrlEnterToSend?: boolean;
 	keyboardShortcuts?: boolean;
+	chatHoverPreview?: boolean;
 	renderMarkdownInPreviews?: boolean;
 	renderMarkdownInUserMessages?: boolean;
 	renderMarkdownInAssistantMessages?: boolean;