load shared chat state

src/App.svelte

@@ -56,6 +56,7 @@
   let collaborationError = '';
   let showCollaboration = false;
   let collaborationGuestId = '';
+  let sharedChatSession: { session_id: string; host_broadcaster_id: string; participants: Array<{ broadcaster_id: string }> } | null = null;
   let oauthLink = '';
   let oauthIdentity: 'streamer' | 'bot' = 'streamer';
   let oauthBusy = false;
@@ -251,8 +252,11 @@
         const invites = await fetch(`${serverAddress}/api/v1/twitch/collaboration/invites?session_id=${encodeURIComponent(collaborationSession.id)}`, { headers: { authorization: `Bearer ${sessionToken}` } });
         if (invites.ok) collaborationInvites = await invites.json();
       }
+      const sharedChat = await fetch(`${serverAddress}/api/v1/twitch/collaboration/shared-chat`, { headers: { authorization: `Bearer ${sessionToken}` } });
+      if (sharedChat.ok) sharedChatSession = await sharedChat.json();
     } catch {
       collaborationSession = null;
+      sharedChatSession = null;
     }
   }