feat(db): add Drizzle ORM setup

Add Drizzle ORM with PostgreSQL for database access. Includes:
- Schema definitions for users, decks, cards, and review_logs tables
- Database connection with node-postgres driver
- Drizzle Kit configuration for migrations
- npm scripts for db:generate, db:migrate, db:push, db:studio

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/pkgs/server/src/db/index.ts b/pkgs/server/src/db/index.ts
new file mode 100644
index 0000000..6730947
--- /dev/null
+++ b/pkgs/server/src/db/index.ts
@@ -0,0 +1,12 @@
+import { drizzle } from "drizzle-orm/node-postgres";
+import * as schema from "./schema";
+
+const databaseUrl = process.env.DATABASE_URL;
+
+if (!databaseUrl) {
+	throw new Error("DATABASE_URL environment variable is not set");
+}
+
+export const db = drizzle(databaseUrl, { schema });
+
+export * from "./schema";