Feat: サーバー初期設定ウィザード (#15954)

* wip

* wip

* Update welcome.setup.vue

* wip

* wip

* wip

* wip

* Update MkServerSetupWizard.vue

* Update MkServerSetupWizard.vue

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* Update types.ts

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* wip

* Update CHANGELOG.md

packages/backend/migration/1746422049376-singleUserMode.js

@@ -0,0 +1,16 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+export class SingleUserMode1746422049376 {
+    name = 'SingleUserMode1746422049376'
+
+    async up(queryRunner) {
+			await queryRunner.query(`ALTER TABLE "meta" ADD "singleUserMode" boolean NOT NULL DEFAULT false`);
+    }
+
+    async down(queryRunner) {
+        await queryRunner.query(`ALTER TABLE "meta" DROP COLUMN "singleUserMode"`);
+    }
+}