perf: add database indexes, implement caching, enforce permission guards, and sanitize external URLs

paperless-backend/src/user-settings/user-settings.controller.ts

@@ -1,5 +1,7 @@
 import { Body, Controller, Get, HttpCode, Post, Put, Request } from '@nestjs/common';
 import { UserSettingsService } from './user-settings.service';
+import { RequirePermissions } from '../auth/permissions.decorator';
+import { Permission } from '../auth/permissions.enum';
 
 @Controller('api/user-settings')
 export class UserSettingsController {
@@ -22,6 +24,7 @@ export class UserSettingsController {
 
   @Post('test-smtp')
   @HttpCode(200)
+  @RequirePermissions(Permission.MANAGE_SETTINGS)
   async testSmtp(@Body() body: { host: string; port: number; secure: boolean; user: string; pass: string }) {
     return this.userSettingsService.testSmtp(body);
   }