패키지 버전 업데이트 및 SvelteKit 3, Tailwind CSS 4로 마이그레이션

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

src/env.ts

@@ -0,0 +1,45 @@
+import { building } from "$app/env";
+import { defineEnvVars } from "@sveltejs/kit/env";
+import ms, { type StringValue } from "ms";
+
+// Empty values (e.g. `LIBRARY_PATH=` in .env) are treated as unset
+
+const required = (value: string | undefined) => {
+  if (!value && !building) throw new Error("Required environment variable not set");
+  return value ?? "";
+};
+
+const optional = (value: string | undefined) => value || undefined;
+
+const withDefault = (defaultValue: string) => (value: string | undefined) => value || defaultValue;
+
+const duration = (defaultValue: StringValue) => (value: string | undefined) => {
+  const result = ms((value || defaultValue) as StringValue);
+  if (!Number.isFinite(result)) throw new Error(`Invalid duration: ${value}`);
+  return result;
+};
+
+export const variables = defineEnvVars({
+  NODE_ENV: { schema: withDefault("development") },
+
+  DATABASE_HOST: { schema: optional },
+  DATABASE_PORT: {
+    schema: (value) => {
+      if (!value) return undefined;
+      const port = Number(value);
+      if (!Number.isInteger(port)) throw new Error(`Invalid port: ${value}`);
+      return port;
+    },
+  },
+  DATABASE_USER: { schema: optional },
+  DATABASE_PASSWORD: { schema: required },
+  DATABASE_NAME: { schema: optional },
+
+  SESSION_SECRET: { schema: required },
+  SESSION_EXPIRES: { schema: duration("14d") },
+  USER_CLIENT_CHALLENGE_EXPIRES: { schema: duration("5m") },
+  SESSION_UPGRADE_CHALLENGE_EXPIRES: { schema: duration("5m") },
+
+  LIBRARY_PATH: { schema: withDefault("library") },
+  THUMBNAILS_PATH: { schema: withDefault("thumbnails") },
+});