fix(web): exclude healthz test from Jest to fix CI failure

The healthz test uses bun:test and NextResponse.json() which requires
Web API globals (Request) not available in Jest jsdom environment.
Other API route tests are already excluded from Jest for similar reasons.

Author: brandonkachen

web/jest.config.cjs

@@ -23,6 +23,7 @@ const config = {
     '<rootDir>/src/lib/__tests__/ban-conditions.test.ts',
     '<rootDir>/src/app/api/v1/.*/__tests__',
     '<rootDir>/src/app/api/agents/publish/__tests__',
+    '<rootDir>/src/app/api/healthz/__tests__',
   ],
 }