feat: add mobile-responsive layout and card views across all pages

- New useIsMobile hook and MobileCardList component
- AppLayout: hamburger menu + Drawer navigation on mobile
- All list pages (Inbox, Posteingang, Manuell, Mail, Freigabe, Zahlung, TaskLog)
  show card layout on mobile instead of tables
- CSS: responsive modal height, horizontal table scroll, text-size-adjust
- Backend: Agrarmonitor polling fixes, Zahlung service improvements,
  IMAP folder service extended, misc controller fixes

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

paperless-frontend/src/pages/PosteingangPage.tsx

@@ -3,14 +3,17 @@ import { Table, Popover, Button, Space, message, Tooltip, Typography } from 'ant
 import { AuthImage } from '../utils/auth-resource';
 import { ReloadOutlined } from '@ant-design/icons';
 
-const { Title } = Typography;
+const { Title, Text } = Typography;
 import dayjs from 'dayjs';
 import { posteingangApi } from '../api/posteingang';
 import type { PosteingangDocument } from '../api/posteingang';
 import DocumentEditModal from '../components/DocumentEditModal';
 import { getEnv } from '../utils/env';
+import { useIsMobile } from '../hooks/useIsMobile';
+import MobileCardList from '../components/MobileCardList';
 
 export default function PosteingangPage() {
+  const isMobile = useIsMobile();
   const [data, setData] = useState<PosteingangDocument[]>([]);
   const [loading, setLoading] = useState(false);
   const [editModalOpen, setEditModalOpen] = useState(false);
@@ -64,6 +67,11 @@ export default function PosteingangPage() {
     />
   );
 
+  const getEingangsdatum = (record: PosteingangDocument) => {
+    const cf = record.customFields?.find((f) => f.field === 9);
+    return cf?.value ? dayjs(cf.value).format('DD.MM.YYYY') : '-';
+  };
+
   const columns = [
     {
       title: 'Vorschau',
@@ -88,10 +96,7 @@ export default function PosteingangPage() {
     {
       title: 'Eingangsdatum',
       key: 'eingangsdatum',
-      render: (_: any, record: PosteingangDocument) => {
-        const cf = record.customFields?.find((f) => f.field === 9);
-        return cf?.value ? dayjs(cf.value).format('DD.MM.YYYY') : '-';
-      }
+      render: (_: any, record: PosteingangDocument) => getEingangsdatum(record),
     },
     {
       title: 'Importiert am',
@@ -121,14 +126,46 @@ export default function PosteingangPage() {
                 </Tooltip>
             </Space>
         </div>
-        <Table 
-          columns={columns} 
-          dataSource={data} 
-          rowKey="id" 
-          loading={loading}
-          pagination={{ pageSize: 20, showSizeChanger: true, showTotal: (t) => `${t} Dokumente` }}
-          locale={{ emptyText: 'Keine Einträge vorhanden' }}
-        />
+        {isMobile ? (
+          <MobileCardList<PosteingangDocument>
+            dataSource={data}
+            rowKey="id"
+            loading={loading}
+            pagination={{ pageSize: 20, showTotal: (t) => `${t} Dokumente` }}
+            renderCard={(record) => (
+              <div style={{ display: 'flex', flexDirection: 'column', gap: 8 }}>
+                <div style={{ display: 'flex', gap: 12 }}>
+                  <AuthImage
+                    src={`${getEnv('VITE_API_URL')}/api/paperless/inbox/preview/${record.id}`}
+                    width={72}
+                    style={{ border: '1px solid #d9d9d9', objectFit: 'contain', flexShrink: 0 }}
+                  />
+                  <div style={{ display: 'flex', flexDirection: 'column', gap: 4, minWidth: 0 }}>
+                    <Text strong>{record.title || '—'}</Text>
+                    <Text type="secondary" style={{ fontSize: 13 }}>
+                      Eingangsdatum: {getEingangsdatum(record)}
+                    </Text>
+                    <Text type="secondary" style={{ fontSize: 13 }}>
+                      Importiert am: {dayjs(record.added).format('DD.MM.YYYY HH:mm')}
+                    </Text>
+                  </div>
+                </div>
+                <Button type="primary" block onClick={() => handleEdit(record)}>
+                  Bearbeiten
+                </Button>
+              </div>
+            )}
+          />
+        ) : (
+          <Table
+            columns={columns}
+            dataSource={data}
+            rowKey="id"
+            loading={loading}
+            pagination={{ pageSize: 20, showSizeChanger: true, showTotal: (t) => `${t} Dokumente` }}
+            locale={{ emptyText: 'Keine Einträge vorhanden' }}
+          />
+        )}
 
         <DocumentEditModal
             documentId={selectedDoc?.id || null}