feat: add complex user invitation and management features

- Implemented complex member and invitation schemas using Zod for validation.
- Created new API endpoints for inviting, accepting, revoking, and canceling complex user invitations.
- Developed handlers for managing complex users, including listing, inviting, revoking, and canceling invitations.
- Added frontend components for displaying and managing complex users and invitations.
- Introduced session storage management for pending invitations.
- Integrated Gravatar for user avatars based on email.
- Created database migration for complex invitations table.

apps/frontend/src/routes/auth-callback.tsx

@@ -1,5 +1,6 @@
 import { apiClient } from '@/lib/api-client';
 import { useAuth } from '@/lib/auth';
+import { acceptStoredPendingInvite } from '@/lib/invitations';
 import { createFileRoute, useNavigate } from '@tanstack/react-router';
 import { useEffect } from 'react';
 
@@ -15,6 +16,7 @@ function AuthCallbackPage() {
       }
 
       try {
+        await acceptStoredPendingInvite(apiClient.complexes.acceptPendingInvitations);
         const complexes = await apiClient.complexes.listMine();
 
         if (complexes.length === 1) {

apps/frontend/src/routes/invite.tsx

@@ -0,0 +1,51 @@
+import { OnboardLoginPage } from '@/features/onboard/onboard-login-page';
+import { apiClient } from '@/lib/api-client';
+import { useAuth } from '@/lib/auth';
+import { acceptStoredPendingInvite, setPendingInvite } from '@/lib/invitations';
+import { createFileRoute, useNavigate } from '@tanstack/react-router';
+import { useEffect } from 'react';
+import { z } from 'zod';
+
+const inviteSearchSchema = z.object({
+  email: z.string().email().optional(),
+  inviteToken: z.string().min(1).optional(),
+});
+
+function InvitePage() {
+  const navigate = useNavigate();
+  const { isAuthenticated } = useAuth();
+  const search = Route.useSearch();
+
+  useEffect(() => {
+    setPendingInvite({
+      email: search.email ?? null,
+      token: search.inviteToken ?? null,
+    });
+  }, [search.email, search.inviteToken]);
+
+  useEffect(() => {
+    if (!isAuthenticated) {
+      return;
+    }
+
+    void (async () => {
+      await acceptStoredPendingInvite(apiClient.complexes.acceptPendingInvitations);
+      await navigate({ to: '/' });
+    })();
+  }, [isAuthenticated, navigate]);
+
+  if (isAuthenticated) {
+    return (
+      <main className="flex min-h-screen w-full items-center justify-center px-6">
+        <p className="text-sm text-muted-foreground">Aceptando invitación...</p>
+      </main>
+    );
+  }
+
+  return <OnboardLoginPage variant="invite" inviteEmail={search.email ?? null} />;
+}
+
+export const Route = createFileRoute('/invite')({
+  validateSearch: inviteSearchSchema,
+  component: InvitePage,
+});