feat: Federation UI polish — modals, backgrounds, scroll, names, blocked

- Federation page uses bg-web5.jpg background
- Invite code in full-screen modal with type label (Link/Peer)
- Join modal upgraded to full-screen with backdrop blur
- "Untrusted" renamed to "Blocked" in trust selector
- Your Nodes / Peers containers: max-h-[60vh] with inner scroll
- Server name from Settings shown on DID card + network map
- DID sync between Web5 and Federation on rotation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

neode-ui/src/views/Dashboard.vue

@@ -435,6 +435,7 @@ const ROUTE_BACKGROUNDS: Record<string, string> = {
   '/dashboard/mesh': 'bg-mesh.jpg',
   '/dashboard/server': 'bg-network.jpg',
   '/dashboard/web5': 'bg-web5.jpg',
+  '/dashboard/federation': 'bg-web5.jpg',
   '/dashboard/settings': 'bg-settings.jpg',
   '/dashboard/chat': 'bg-aiui.jpg',
 }