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

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

src/trpc/schemas.ts

@@ -0,0 +1,13 @@
+import { z } from "zod";
+
+export const IdSchema = z.int().positive();
+export const DirectoryIdSchema = z.union([z.literal("root"), IdSchema]);
+export const CategoryIdSchema = z.union([z.literal("root"), IdSchema]);
+export const Base64Schema = z.base64().nonempty();
+
+export const EncryptedNameSchema = {
+  name: Base64Schema,
+  nameIv: Base64Schema,
+};
+
+export const toCiphertext = (ciphertext: string, iv: string) => ({ ciphertext, iv });