refactor: inline packages/db and packages/types into api package

Phase 2 extraction: groombook/api from groombook/app monorepo.

Changes:
- Move packages/db content to apps/api/src/db/
- Move packages/types content to apps/api/src/types/
- Inline database schema and migrations into api package
- Update Dockerfile to build single package
- Update CI workflow for single-package structure
- Fix vitest.config.ts aliases

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/services/waitlistNotify.ts

@@ -1,4 +1,4 @@
-import { and, eq, getDb, waitlistEntries, clients, pets, services } from "./packages/db";
+import { and, eq, getDb, waitlistEntries, clients, pets, services } from "../db";
 import { buildWaitlistNotificationEmail, sendEmail } from "./email.js";
 
 export async function notifyWaitlistForAppointment(