서버 코드를 Router, Service, Repository 계층으로 분리하고 오류 처리 및 파일 삭제 로직 개선

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

kysely.config.ts

@@ -1,17 +1,17 @@
 import { defineConfig } from "kysely-ctl";
-import { Pool } from "pg";
+import { createDialect } from "./src/lib/server/db/dialect";
+
+// Empty values (e.g. `DATABASE_HOST=` in .env) are treated as unset, as in src/env.ts
+const optional = (name: string) => process.env[name] || undefined;
 
 export default defineConfig({
-  dialect: "pg",
-  dialectConfig: {
-    pool: new Pool({
-      host: process.env.DATABASE_HOST,
-      port: process.env.DATABASE_PORT ? parseInt(process.env.DATABASE_PORT) : undefined,
-      user: process.env.DATABASE_USER,
-      password: process.env.DATABASE_PASSWORD,
-      database: process.env.DATABASE_NAME,
-    }),
-  },
+  dialect: createDialect({
+    host: optional("DATABASE_HOST"),
+    port: optional("DATABASE_PORT") ? Number(optional("DATABASE_PORT")) : undefined,
+    user: optional("DATABASE_USER"),
+    password: optional("DATABASE_PASSWORD"),
+    name: optional("DATABASE_NAME"),
+  }),
   migrations: {
     migrationFolder: "./src/lib/server/db/migrations",
   },