feat: directus插件与组合式函数编写

- plugins：Directus插件
- composable：Directus图片/文件的相关组合式函数

app/plugins/directus.ts

@@ -0,0 +1,12 @@
+import { createDirectus, rest, staticToken } from '@directus/sdk';
+
+export default defineNuxtPlugin(() => {
+  const config = useRuntimeConfig();
+
+  const directus = createDirectus<Schema>(config.public.directus.url)
+    .with(rest())
+    .with(staticToken(config.public.directus.token || ''));
+  return {
+    provide: { directus },
+  };
+});