feat(mcp): Dateien ohne Base64 per HTTP hochladen

- POST /api/mcp/files nimmt multipart/form-data oder Rohdaten mit dem MCP-Token an, Ziel Dokumentenablage oder Eingangsrechnung
- documents.files.upload_url liefert Adresse, Parameter und curl-Beispiele
- Upload einer Eingangsrechnung bereitet nur noch die hochgeladene Datei vor

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

backend/src/routes/mcp.ts

@@ -11,6 +11,11 @@ import { s3 } from "../utils/s3"
 import { secrets } from "../utils/secrets"
 import { GetObjectCommand } from "@aws-sdk/client-s3"
 import { sanitizeFilename } from "../utils/filename"
+import multipart from "@fastify/multipart"
+import { MCP_FILE_LIMIT } from "../mcp/documentFiles"
+import { parseUploadQuery, storeMcpFileUpload } from "../mcp/fileUploads"
+
+const RAW_UPLOAD_TYPES = ["application/pdf", "application/octet-stream", "application/xml", "text/xml", "image/jpeg", "image/png", "image/tiff"]
 
 const SUPPORTED_PROTOCOL_VERSIONS = [
     "2025-11-25",
@@ -62,7 +67,13 @@ const requireMcpTokenManagementPermission = (req: any) => {
     throw Object.assign(new Error("Fehlende Berechtigung: mcp.tokens.write"), { statusCode: 403 })
 }
 
-export default async function mcpRoutes(server: FastifyInstance) {
+type McpRouteOptions = {
+    /** Replaceable in tests to avoid object storage. */
+    storeUpload?: typeof storeMcpFileUpload
+}
+
+export default async function mcpRoutes(server: FastifyInstance, options: McpRouteOptions = {}) {
+    const storeUpload = options.storeUpload || storeMcpFileUpload
     server.get("/mcp/tokens", async (req, reply) => {
         try {
             requireMcpTokenManagementPermission(req)
@@ -221,6 +232,37 @@ export default async function mcpRoutes(server: FastifyInstance) {
         }
     })
 
+    // Binary uploads without Base64; parsers stay scoped so JSON-RPC parsing is unaffected.
+    await server.register(async (uploads) => {
+        await uploads.register(multipart, { limits: { fileSize: MCP_FILE_LIMIT, files: 1 } })
+        uploads.addContentTypeParser(RAW_UPLOAD_TYPES, { parseAs: "buffer", bodyLimit: MCP_FILE_LIMIT }, (_req, body, done) => done(null, body))
+
+        uploads.post("/mcp/files", async (req, reply) => {
+            try {
+                const context = await createMcpContext(server, req)
+                const query = parseUploadQuery(req.query as Record<string, unknown>)
+                let body: Buffer
+                let filename = query.filename
+                let mimeType = req.headers["content-type"]?.split(";")[0].trim() || null
+                if (req.isMultipart()) {
+                    const part = await req.file()
+                    if (!part || part.fieldname !== "file") return reply.code(400).send({ error: "Bitte die Datei im Feld file übertragen." })
+                    body = await part.toBuffer()
+                    filename ||= part.filename
+                    mimeType = part.mimetype
+                } else if (Buffer.isBuffer(req.body)) {
+                    body = req.body
+                } else {
+                    return reply.code(415).send({ error: `Bitte multipart/form-data oder einen der Content-Types ${RAW_UPLOAD_TYPES.join(", ")} verwenden.` })
+                }
+                if (!filename) return reply.code(400).send({ error: "filename ist erforderlich." })
+                return await storeUpload(context, { ...query, filename, body, mimeType })
+            } catch (error) {
+                return reply.code((error as any)?.statusCode || 400).send({ error: error instanceof Error ? error.message : "Upload fehlgeschlagen." })
+            }
+        })
+    })
+
     server.post("/mcp", { bodyLimit: MCP_BODY_LIMIT }, async (req, reply) => {
         const body = req.body as JsonRpcRequest | JsonRpcRequest[]
         const requests = Array.isArray(body) ? body : [body]