pets.ts imports pets, appointments, and, eq, exists, or directly from
"../db". The vi.mock factory only returned getDb, causing vitest to throw
"No 'pets' export is defined" and 7 tests to get 400 instead of 201/200.
Fix adds the missing named exports to the mock return object.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>