fix: stabilize useQuery mock reference to prevent infinite re-render loop in AgentOutputViewer test

apps/web/src/components/AgentOutputViewer.test.tsx

@@ -5,10 +5,11 @@ import { vi, describe, it, expect, beforeEach } from 'vitest'
 import * as parseModule from '@/lib/parse-agent-output'
 import { AgentOutputViewer } from './AgentOutputViewer'
 
+const EMPTY_CHUNKS: never[] = []
 vi.mock('@/lib/trpc', () => ({
   trpc: {
     getAgentOutput: {
-      useQuery: vi.fn(() => ({ data: [], isLoading: false })),
+      useQuery: vi.fn(() => ({ data: EMPTY_CHUNKS, isLoading: false })),
     },
     onAgentOutput: {
       useSubscription: vi.fn(),