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/backend/src/modules/complex/handlers/list-complex-users.handler.ts

@@ -0,0 +1,14 @@
+import { getComplexUsersOverview } from '@/modules/complex/services/complex-members.service';
+import type { AppContext } from '@/types/hono';
+import { z } from 'zod';
+
+const complexParamsSchema = z.object({
+  id: z.uuid(),
+});
+
+export async function listComplexUsersHandler(c: AppContext) {
+  const user = c.get('user');
+  const params = complexParamsSchema.parse(c.req.param());
+  const result = await getComplexUsersOverview(user.id, params.id);
+  return c.json(result);
+}