feat: use app name in window titles for NIP-89 app events

Add special handling for kind 31990 (Application Handler) events in
getEventDisplayTitle to use the app name from content JSON instead of
generic kind name. Falls back to identifier if app name not available.

This gives NIP-89 app handler events nice readable window titles.

src/lib/event-title.ts

@@ -9,6 +9,7 @@ import {
   getPullRequestSubject,
 } from "@/lib/nip34-helpers";
 import { getCodeName } from "@/lib/nip-c0-helpers";
+import { getAppName } from "@/lib/nip89-helpers";
 import { getKindInfo } from "@/constants/kinds";
 
 /**
@@ -48,6 +49,9 @@ export function getEventDisplayTitle(
     case 1618: // Pull request
       title = getPullRequestSubject(event);
       break;
+    case 31990: // Application Handler
+      title = getAppName(event);
+      break;
   }
 
   if (title) return title;