feat(db): Drizzle ORM schema and migrations

Schema domains: users/auth, recipes, social, meal-planning, tiers/usage, webhooks.
Includes Better Auth tables, audit_logs, site_settings, push_subscriptions,
user_model_prefs, user_nutrition_goals. Migrations 0000–0008 applied.

packages/db/src/index.ts

@@ -0,0 +1,5 @@
+export { db } from "./client";
+export type { Db } from "./client";
+export * from "./schema";
+// Re-export query helpers so all callers use the same drizzle-orm instance
+export { eq, and, or, desc, asc, gt, lt, gte, lte, ne, inArray, isNull, isNotNull, sql, count, avg, sum, min, max, ilike, like } from "drizzle-orm";