fix(ui): Invite a Peer sends trust_level=observer to federation.invite

The invite type chosen in QuickActions was only used for the modal
title — the RPC never carried it, so every invite was minted Trusted.
Pass it through so 'Invite a Peer' mints observer invites and 'Link
Your Nodes' keeps trusted ones.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

neode-ui/src/api/rpc-client.ts

@@ -668,10 +668,12 @@ class RPCClient {
   }
 
   // Federation
-  async federationInvite(): Promise<{ code: string; did: string; onion: string }> {
+  async federationInvite(
+    trustLevel: 'trusted' | 'observer' = 'trusted'
+  ): Promise<{ code: string; did: string; onion: string; trust_level: string }> {
     return this.call({
       method: 'federation.invite',
-      params: {},
+      params: { trust_level: trustLevel },
     })
   }