db: drizzle schema matching spec 02, initial migrations, settings service

Migration 0000 enables citext; 0001 creates all 39 tables. DB tests use a
throwaway database per file (TEST_DATABASE_URL, derived from .env in dev,
a postgres service in CI). Decision 0002: pg driver and @fastify/cookie.

Task: M1-T1

apps/web/package.json

@@ -13,7 +13,8 @@
     "@selfphoneng/shared": "workspace:*",
     "react": "^19.3.1",
     "react-dom": "^19.3.1",
-    "react-router": "^8.4.0"
+    "react-router": "^8.4.0",
+    "zod": "^4.6.7"
   },
   "devDependencies": {
     "@tailwindcss/vite": "^4.3.3",