feat(db): 配置 Drizzle ORM 与 PostgreSQL 静态连接池

src/db/index.ts

@@ -0,0 +1,20 @@
+import { drizzle } from "drizzle-orm/postgres-js";
+import postgres from "postgres";
+import type { PostgresJsDatabase } from "drizzle-orm/postgres-js";
+import dotenv from "dotenv";
+
+dotenv.config();
+
+const connectionString = process.env.DATABASE_URL!;
+const driver = postgres(connectionString, { max: 1 });
+let db: PostgresJsDatabase = drizzle(driver);
+
+if (process.env.NODE_ENV !== "production") {
+  const g = globalThis as unknown as { drizzleClient: PostgresJsDatabase };
+  if (!g.drizzleClient) {
+    g.drizzleClient = db;
+  }
+  db = g.drizzleClient;
+}
+
+export { db };