feat(db): add PostgreSQL connection and schema definitions

databases/db.ts

@@ -0,0 +1,14 @@
+import { drizzle } from "npm:drizzle-orm/node-postgres";
+import pg from "npm:pg";
+
+const { Pool } = pg;
+
+const pool = new Pool({
+  host: Deno.env.get("POSTGRES_HOST"),
+  port: Number(Deno.env.get("POSTGRES_PORT") ?? 5432),
+  user: Deno.env.get("POSTGRES_USER"),
+  password: Deno.env.get("POSTGRES_PASS"),
+  database: Deno.env.get("POSTGRES_DB"),
+});
+
+export const db = drizzle(pool);