PdfDragButton: PDF per Drag-and-Drop aus Bankkarte/Ausweis ziehen

Neue wiederverwendbare Komponente PdfDragButton: ziehbares Element,
mit dem der hinterlegte Scan direkt aus dem Browser in ein Mail-Fenster
(Anhang) oder den Datei-Explorer gezogen werden kann (Chromium-
DownloadURL, Format <mime>:<name>:<absolute-url>).

Bewusste Plattform-Grenze: PDF per Strg+V als Datei einfuegen geht im
Browser nicht (Web-Clipboard darf keine OS-Datei-Zwischenablage
befuellen) -> Drag-and-Drop. DownloadURL nur Chrome/Edge, nicht
Firefox (dort Klick-Fallback: Datei im Tab oeffnen).

Eingebaut an: ContractForm (neben IBAN/Ausweisnummer-Copy), Vertrags-
ansicht (Bankkarte/Ausweis-Card), Kundenakte-Tabs Bankkarten+Ausweise.
Nur bei vorhandenem documentPath. Nutzt bestehende fileUrl()-Download-
URL (Token als Query, Per-File-Ownership-Check unveraendert) - kein
neuer Endpoint, keine neue Angriffsflaeche.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/pages/contracts/ContractDetail.tsx

@@ -19,6 +19,7 @@ import toast from 'react-hot-toast';
 import JpgToPdfModal from '../../components/ui/JpgToPdfModal';
 import { calculateConsumption, calculateCosts, calculateMultiMeterConsumption } from '../../utils/energyCalculations';
 import CopyButton, { CopyableBlock } from '../../components/ui/CopyButton';
+import PdfDragButton from '../../components/ui/PdfDragButton';
 import AutosaveDateInput from '../../components/ui/AutosaveDateInput';
 import { formatDate } from '../../utils/dateFormat';
 import { useProviderSettings } from '../../hooks/useProviderSettings';
@@ -2651,6 +2652,14 @@ export default function ContractDetail() {
               {c.bankCard.iban}
               <CopyButton value={c.bankCard.iban} />
             </p>
+            {c.bankCard.documentPath && (
+              <div className="mt-1">
+                <PdfDragButton
+                  path={c.bankCard.documentPath}
+                  filename={`Bankkarte-${c.bankCard.iban}`}
+                />
+              </div>
+            )}
             {c.bankCard.bankName && <p className="text-gray-500">{c.bankCard.bankName}</p>}
             {c.bankCard.description && (
               <p className="text-sm text-gray-600 mt-1 italic whitespace-pre-line">
@@ -2666,6 +2675,14 @@ export default function ContractDetail() {
               <CopyButton value={c.identityDocument.documentNumber} />
             </p>
             <p className="text-gray-500">{c.identityDocument.type}</p>
+            {c.identityDocument.documentPath && (
+              <div className="mt-1">
+                <PdfDragButton
+                  path={c.identityDocument.documentPath}
+                  filename={`Ausweis-${c.identityDocument.documentNumber}`}
+                />
+              </div>
+            )}
           </Card>
         )}
       </div>

frontend/src/pages/contracts/ContractForm.tsx

@@ -10,6 +10,7 @@ import Button from '../../components/ui/Button';
 import Input from '../../components/ui/Input';
 import Select from '../../components/ui/Select';
 import CopyButton from '../../components/ui/CopyButton';
+import PdfDragButton from '../../components/ui/PdfDragButton';
 import CustomerInfoModal from '../../components/contracts/CustomerInfoModal';
 import { buildContractLabelParts } from '../../utils/contractLabel';
 import type { ContractType } from '../../types';
@@ -978,6 +979,12 @@ export default function ContractForm() {
                     {selectedBankCard && (
                       <CopyButton value={selectedBankCard.iban} title="IBAN kopieren" />
                     )}
+                    {selectedBankCard?.documentPath && (
+                      <PdfDragButton
+                        path={selectedBankCard.documentPath}
+                        filename={`Bankkarte-${selectedBankCard.iban}`}
+                      />
+                    )}
                   </span>
                 }
                 {...register('bankCardId')}
@@ -1004,6 +1011,12 @@ export default function ContractForm() {
                     {selectedDocument && (
                       <CopyButton value={selectedDocument.documentNumber} title="Ausweisnummer kopieren" />
                     )}
+                    {selectedDocument?.documentPath && (
+                      <PdfDragButton
+                        path={selectedDocument.documentPath}
+                        filename={`Ausweis-${selectedDocument.documentNumber}`}
+                      />
+                    )}
                   </span>
                 }
                 {...register('identityDocumentId')}

frontend/src/pages/customers/CustomerDetail.tsx

@@ -18,6 +18,7 @@ import FileUpload from '../../components/ui/FileUpload';
 import { Edit, Plus, Trash2, MapPin, CreditCard, FileText, Gauge, Eye, EyeOff, Download, Globe, UserPlus, X, Search, Mail, Copy, Check, ChevronDown, ChevronRight, Info, Shield, ShieldCheck, ShieldX, ShieldAlert, Lock, ArrowLeft, Cake, RefreshCw, ExternalLink, Images } from 'lucide-react';
 import JpgToPdfModal from '../../components/ui/JpgToPdfModal';
 import CopyButton, { CopyableBlock } from '../../components/ui/CopyButton';
+import PdfDragButton from '../../components/ui/PdfDragButton';
 import BirthdayManagementModal from '../../components/BirthdayManagementModal';
 import { formatDate } from '../../utils/dateFormat';
 import { getContractTypeInfo } from '../../utils/contractInfo';
@@ -1002,6 +1003,10 @@ function BankCardsTab({
                       <Download className="w-4 h-4" />
                       Download
                     </a>
+                    <PdfDragButton
+                      path={card.documentPath}
+                      filename={`Bankkarte-${card.iban}`}
+                    />
                     {canEdit && (
                       <>
                         <FileUpload
@@ -1238,6 +1243,10 @@ function DocumentsTab({
                       <Download className="w-4 h-4" />
                       Download
                     </a>
+                    <PdfDragButton
+                      path={doc.documentPath}
+                      filename={`Ausweis-${doc.documentNumber}`}
+                    />
                     {canEdit && (
                       <>
                         <FileUpload