fix: add missing existsSync to fs mock in processor tests

worker/__tests__/processor.test.ts

@@ -12,6 +12,7 @@ jest.mock('@/lib/prisma', () => ({
 jest.mock('@/lib/token')
 jest.mock('child_process')
 jest.mock('fs', () => ({
+  existsSync: jest.fn(() => false),
   readdirSync: jest.fn(() => ['uuid-abc.mp4']),
   statSync: jest.fn(() => ({ size: 1024 })),
 }))