feat: implement ProcessVerarbeiteteDocuments (Upload-Check)

Ported ProcessVerarbeiteteDocuments() from C# ProcessUploads.cs:
- Checks docs tagged "hochgeladen" → eingangsrechnungVorhanden()
- On match: livesearch, update title/type/created/correspondent/tags,
  set custom fields (externeBelegnummer, AgrarmonitorLink), addNote
- Tag "hochgeladen" → "fertig" swap; owner via Client.AgrarmonitorBetriebId
- 401/403 guard: clearClient() + break (same pattern as runPolling)
- Cron: AGRARMONITOR_UPLOAD_CHECK_CRON (default: 0 * * * * *)
- New settings: agrarmonitor_tag_hochgeladen, agrarmonitor_link_field
- Endpoint: POST /api/agrarmonitor/process-uploads
- Frontend: polling-config extended with tagHochgeladen + linkField select,
  new card "Dokumenten-Verarbeitung" with run button + result display

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

paperless-frontend/src/api/settings.ts

@@ -199,6 +199,8 @@ export interface AgrarmonitorStatusData {
 export interface AgrarmonitorPollingConfig {
   tagFertig: string;
   tagVerbucht: string;
+  tagHochgeladen: string;
+  linkField: string;
 }
 
 export interface AgrarmonitorPollingResult {
@@ -221,4 +223,6 @@ export const agrarmonitorApi = {
     api.put<AgrarmonitorPollingConfig>('/api/agrarmonitor/polling-config', config).then((r) => r.data),
   runPolling: () =>
     api.post<AgrarmonitorPollingResult>('/api/agrarmonitor/run-polling').then((r) => r.data),
+  processUploads: () =>
+    api.post<AgrarmonitorPollingResult>('/api/agrarmonitor/process-uploads').then((r) => r.data),
 };

paperless-frontend/src/pages/SettingsPage.tsx

@@ -2291,9 +2291,12 @@ function AgrarmonitorTab() {
   const [pollingConfigLoading, setPollingConfigLoading] = useState(false);
   const [pollingSaving, setPollingSaving] = useState(false);
   const [pollingRunning, setPollingRunning] = useState(false);
+  const [uploadCheckRunning, setUploadCheckRunning] = useState(false);
   const [status, setStatus] = useState<AgrarmonitorStatusData | null>(null);
   const [registerResult, setRegisterResult] = useState<{ success: boolean; message: string } | null>(null);
   const [pollingResult, setPollingResult] = useState<AgrarmonitorPollingResult | null>(null);
+  const [uploadCheckResult, setUploadCheckResult] = useState<AgrarmonitorPollingResult | null>(null);
+  const [customFields, setCustomFields] = useState<PaperlessCustomField[]>([]);
 
   const handleLoadStatus = async () => {
     setLoading(true);
@@ -2341,7 +2344,10 @@ function AgrarmonitorTab() {
     }
   }, [pollingForm]);
 
-  useEffect(() => { handleLoadPollingConfig(); }, [handleLoadPollingConfig]);
+  useEffect(() => {
+    handleLoadPollingConfig();
+    paperlessApi.getCustomFields().then(setCustomFields).catch(() => {});
+  }, [handleLoadPollingConfig]);
 
   const handleSavePollingConfig = async () => {
     const values = await pollingForm.validateFields() as AgrarmonitorPollingConfig;
@@ -2369,6 +2375,19 @@ function AgrarmonitorTab() {
     }
   };
 
+  const handleProcessUploads = async () => {
+    setUploadCheckRunning(true);
+    setUploadCheckResult(null);
+    try {
+      const result = await agrarmonitorApi.processUploads();
+      setUploadCheckResult(result);
+    } catch {
+      message.error('Upload-Check fehlgeschlagen');
+    } finally {
+      setUploadCheckRunning(false);
+    }
+  };
+
   const renderStatusTag = (value: boolean | null, labelTrue: string, labelFalse: string) => {
     if (value === null) return <Tag>–</Tag>;
     return value
@@ -2462,6 +2481,16 @@ function AgrarmonitorTab() {
             >
               <Input placeholder="9" style={{ width: 120 }} />
             </Form.Item>
+            <Form.Item name="tagHochgeladen" label="Tag-ID: Hochgeladen in Agrarmonitor">
+              <Input placeholder="3" style={{ width: 120 }} />
+            </Form.Item>
+            <Form.Item name="linkField" label="Custom Field: Agrarmonitor-Link">
+              <Select allowClear placeholder="Kein Feld ausgewählt" style={{ width: 280 }}>
+                {customFields.map(f => (
+                  <Select.Option key={f.id} value={String(f.id)}>{f.id}: {f.name}</Select.Option>
+                ))}
+              </Select>
+            </Form.Item>
             <Button type="primary" loading={pollingSaving} onClick={handleSavePollingConfig}>
               Speichern
             </Button>
@@ -2492,6 +2521,35 @@ function AgrarmonitorTab() {
             )}
           </Space>
         </Card>
+
+        <Card size="small" title="Dokumenten-Verarbeitung">
+          <Typography.Text type="secondary" style={{ display: 'block', marginBottom: 12 }}>
+            Prüft Belege mit Tag "Hochgeladen in Agrarmonitor" und setzt den Tag auf "AMfertig",
+            sobald sie im Agrarmonitor-Buchungssystem erscheinen.
+          </Typography.Text>
+          <Space direction="vertical" style={{ width: '100%' }}>
+            <Button loading={uploadCheckRunning} onClick={handleProcessUploads}>
+              Jetzt prüfen
+            </Button>
+            {uploadCheckResult && (
+              <div>
+                <Tag color="blue">{uploadCheckResult.processed} geprüft</Tag>
+                <Tag color="success">{uploadCheckResult.updated} aktualisiert</Tag>
+                <Tag>{uploadCheckResult.skipped} übersprungen</Tag>
+                {uploadCheckResult.errors.length > 0 && (
+                  <Tag color="error">{uploadCheckResult.errors.length} Fehler</Tag>
+                )}
+                {uploadCheckResult.errors.length > 0 && (
+                  <ul style={{ marginTop: 8, paddingLeft: 20 }}>
+                    {uploadCheckResult.errors.map((e, i) => (
+                      <li key={i} style={{ color: '#ff4d4f' }}>{e}</li>
+                    ))}
+                  </ul>
+                )}
+              </div>
+            )}
+          </Space>
+        </Card>
       </Space>
     </div>
   );