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/drizzle/0000_milky_black_cat.sql

@@ -0,0 +1,7 @@
+CREATE TABLE "users" (
+	"id" text PRIMARY KEY NOT NULL,
+	"email" text NOT NULL,
+	"password_hash" text NOT NULL,
+	"created_at" timestamp DEFAULT now() NOT NULL,
+	CONSTRAINT "users_email_unique" UNIQUE("email")
+);