feat(backend): Webhooks mit HMAC-signierter Auslieferung (Modul 28)

WebhooksModule (WebhookSubscription: URL, Events, Secret, aktiv) mit
Event-Dispatcher, angehaengt an 10 Ereignisse in 8 bestehenden Services
(colony.created, inspection.created, queen.created, queen.replaced,
harvest.created, batch.created, batch.updated, product.stock_changed,
task.created, task.completed). Auslieferung ist best-effort und blockiert
die ausloesende Anfrage nicht bei Fehlern.

ApiCore-Backend/src/tasks/tasks.service.ts

@@ -1,6 +1,7 @@
 import { Injectable, NotFoundException } from '@nestjs/common';
 import { PrismaService } from '../prisma/prisma.service';
 import { AuditLogService } from '../audit/audit-log.service';
+import { WebhooksService } from '../webhooks/webhooks.service';
 import { Task, TaskPriority, TaskStatus } from '../../generated/prisma';
 import { CreateTaskDto } from './dto/create-task.dto';
 import { UpdateTaskDto } from './dto/update-task.dto';
@@ -15,6 +16,7 @@ export class TasksService {
   constructor(
     private readonly prisma: PrismaService,
     private readonly auditLog: AuditLogService,
+    private readonly webhooks: WebhooksService,
   ) {}
 
   async findAll(filter: TaskFilter): Promise<Task[]> {
@@ -47,6 +49,7 @@ export class TasksService {
       userId: actingUserId,
       afterData: task,
     });
+    await this.webhooks.dispatch('task.created', task);
     return task;
   }
 
@@ -88,6 +91,7 @@ export class TasksService {
       beforeData: before,
       afterData: task,
     });
+    await this.webhooks.dispatch('task.completed', task);
     return task;
   }
 }