feat(01-01): define DB schema, configure Drizzle Kit, write seed script

- Created src/lib/db/schema.ts with users table (id, email, password_hash, created_at)
- Created src/lib/db/index.ts exporting db singleton via Drizzle + Neon HTTP driver
- Created drizzle.config.ts pointing to schema.ts with postgresql dialect
- Created scripts/seed.ts reading AGENT_EMAIL/AGENT_PASSWORD to create hashed user row
- Generated drizzle/0000_milky_black_cat.sql migration (committed per user decision)
- db:migrate and db:seed pending user Neon database setup

teressa-copeland-homes/src/lib/db/index.ts

@@ -0,0 +1,6 @@
+import { drizzle } from "drizzle-orm/neon-http";
+import { neon } from "@neondatabase/serverless";
+import * as schema from "./schema";
+
+const sql = neon(process.env.DATABASE_URL!);
+export const db = drizzle({ client: sql, schema });