feat: preserved usernames

Resolve #10704

packages/backend/src/server/api/endpoints/admin/update-meta.ts

@@ -95,6 +95,7 @@ export const paramDef = {
 		enableChartsForRemoteUser: { type: 'boolean' },
 		enableChartsForFederatedInstances: { type: 'boolean' },
 		serverRules: { type: 'array', items: { type: 'string' } },
+		preservedUsernames: { type: 'array', items: { type: 'string' } },
 	},
 	required: [],
 } as const;
@@ -392,6 +393,10 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 				set.serverRules = ps.serverRules;
 			}
 
+			if (ps.preservedUsernames !== undefined) {
+				set.preservedUsernames = ps.preservedUsernames;
+			}
+
 			await this.metaService.update(set);
 			this.moderationLogService.insertModerationLog(me, 'updateMeta');
 		});