chore: 著作権とライセンスについての情報を各ファイルに追加する (#11348)

* chore: Add the SPDX information to each file

Add copyright and licensing information as defined in version 3.0 of
the REUSE Specification.

* tweak format

---------

Co-authored-by: syuilo <Syuilotan@yahoo.co.jp>

packages/backend/src/core/FetchInstanceMetadataService.ts

@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and other misskey contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import { URL } from 'node:url';
 import { Inject, Injectable } from '@nestjs/common';
 import { JSDOM } from 'jsdom';
@@ -70,9 +75,9 @@ export class FetchInstanceMetadataService {
 					return;
 				}
 			}
-	
+
 			this.logger.info(`Fetching metadata of ${instance.host} ...`);
- 
+
 			const [info, dom, manifest] = await Promise.all([
 				this.fetchNodeinfo(instance).catch(() => null),
 				this.fetchDom(instance).catch(() => null),