Focused validation

Command
  ../../../../node_modules/.bin/vitest run __tests__/api/agents.test.ts __tests__/components/agents-list.test.tsx

Result
  ✓ __tests__/api/agents.test.ts (14 tests)
  ✓ __tests__/components/agents-list.test.tsx (2 tests)
  Test Files  2 passed
  Tests       16 passed

Coverage of the fix
  - API route retries with developer:developers(display_name) when billing columns drift.
  - AgentsList keeps rendering stale directory cards when background refetch fails after SSR data exists.
