fix: update header after auth via requireAuth flow

When a user authenticates through the community creation form (via
requireAuth), the header bar now re-renders to show the logged-in
state instead of still displaying the Sign In button.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/rspace-header.ts

@@ -433,6 +433,7 @@ interface AuthModalCallbacks {
 }
 
 let activeModal: HTMLElement | null = null;
+let headerRenderFn: (() => void) | null = null;
 
 /**
  * Show the EncryptID auth modal for sign-in or registration.
@@ -761,6 +762,9 @@ export function mountHeader(options: HeaderOptions): void {
     });
   }
 
+  // Store render function so requireAuth can update the header after auth
+  headerRenderFn = renderHeader;
+
   // Mount to DOM
   document.body.prepend(header);
   renderHeader();
@@ -775,6 +779,11 @@ export function requireAuth(onAuthenticated: () => void): boolean {
   if (isAuthenticated()) {
     return true;
   }
-  showAuthModal({ onSuccess: onAuthenticated });
+  showAuthModal({
+    onSuccess: () => {
+      headerRenderFn?.();
+      onAuthenticated();
+    },
+  });
   return false;
 }