feat(accounting): Kostenstellen von Eingangsbelegen jederzeit nachträglich ändern

Eigener Endpunkt und MCP-Tool ändern ausschließlich die Positionskostenstellen,
auch bei gebuchten oder einer Bankbuchung zugewiesenen Eingangsbelegen.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

backend/src/routes/functions.ts

@@ -22,6 +22,7 @@ import {citys, files} from "../../db/schema";
 import {and, eq, isNull, not} from "drizzle-orm";
 import {cancelManualGeneration, executeManualGeneration, finishManualGeneration} from "../modules/serialexecution.service";
 import { updateOutgoingDocumentCostCentres } from "../modules/outgoing-document-cost-centres.service";
+import { updateIncomingInvoiceCostCentres } from "../modules/incoming-invoice-cost-centres.service";
 import { s3 } from "../utils/s3";
 import { secrets } from "../utils/secrets";
 import { storeExtractedTextForFile } from "../utils/documentText";
@@ -334,6 +335,26 @@ export default async function functionRoutes(server: FastifyInstance) {
         }
     })
 
+    server.put('/functions/incoming-invoices/:id/cost-centres', async (req, reply) => {
+        try {
+            const { id } = req.params as { id: string }
+            const invoiceId = Number(id)
+            if (!Number.isFinite(invoiceId)) return reply.code(400).send({ error: "Ungültige Eingangsbeleg-ID" })
+
+            const invoice = await updateIncomingInvoiceCostCentres(
+                server,
+                req.user.tenant_id,
+                req.user.user_id,
+                invoiceId,
+                req.body as any,
+            )
+            return { invoice }
+        } catch (error) {
+            const statusCode = (error as any)?.statusCode || 500
+            return reply.code(statusCode).send({ error: error instanceof Error ? error.message : "Kostenstellen konnten nicht geändert werden" })
+        }
+    })
+
     server.post('/functions/services/bankstatementsync', async (req, reply) => {
         const result = await server.services.bankStatements.run(req.user.tenant_id);
         if (result.errors.length > 0) {