fix(backend): DELETE /webhooks/:id returns 204 No Content

Matches REST convention and the frontend api-client's existing 204
fast-path, avoiding a JSON-parse crash on an empty response body.

ApiCore-Backend/src/webhooks/webhooks.controller.ts

@@ -1,4 +1,12 @@
-import { Body, Controller, Delete, Get, Param, Post } from '@nestjs/common';
+import {
+  Body,
+  Controller,
+  Delete,
+  Get,
+  HttpCode,
+  Param,
+  Post,
+} from '@nestjs/common';
 import { ApiBearerAuth, ApiTags } from '@nestjs/swagger';
 import { Role } from '../../generated/prisma';
 import { Roles } from '../auth/decorators/roles.decorator';
@@ -28,6 +36,7 @@ export class WebhooksController {
   }
 
   @Delete(':id')
+  @HttpCode(204)
   delete(@Param('id') id: string, @CurrentUser() actor: AuthenticatedUser) {
     return this.webhooksService.delete(id, actor.id);
   }