feat: improve frontend accessibility, dark mode, and UX

- Replace div with semantic button elements in AppLayout for accessibility
- Use Ant Design theme tokens instead of hardcoded colors in MailDetailPage
- Add loading state to refresh buttons and pagination info
- Add German empty state messages to tables
- Clean up unnecessary ConfigProvider wrappers

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

paperless-frontend/src/pages/ManuellBearbeitenPage.tsx

@@ -1,5 +1,7 @@
 import { useEffect, useState } from 'react';
-import { Table, Popover, Button, Space, message, ConfigProvider, Tooltip } from 'antd';
+import { Table, Popover, Button, Space, message, Tooltip, Typography } from 'antd';
+
+const { Title } = Typography;
 import { ReloadOutlined } from '@ant-design/icons';
 import dayjs from 'dayjs';
 import { posteingangApi } from '../api/posteingang';
@@ -97,7 +99,7 @@ export default function ManuellBearbeitenPage() {
       render: (text: string) => dayjs(text).format('DD.MM.YYYY HH:mm'),
     },
     {
-      title: 'Aktion',
+      title: 'Aktionen',
       key: 'action',
       width: 150,
       render: (_: any, record: PosteingangDocument) => (
@@ -109,10 +111,9 @@ export default function ManuellBearbeitenPage() {
   ];
 
   return (
-    <ConfigProvider>
-      <div style={{ padding: '0 24px 24px' }}>
-        <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginBottom: 16 }}>
-            <h2>Manuell bearbeiten</h2>
+    <div>
+      <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginBottom: 16 }}>
+            <Title level={3} style={{ margin: 0 }}>Manuell bearbeiten</Title>
             <Space>
                 <Tooltip title="Manuell aktualisieren">
                     <Button icon={<ReloadOutlined />} onClick={fetchData} loading={loading} />
@@ -124,9 +125,10 @@ export default function ManuellBearbeitenPage() {
           dataSource={data} 
           rowKey="id" 
           loading={loading}
-          pagination={{ pageSize: 20 }}
+          pagination={{ pageSize: 20, showSizeChanger: true, showTotal: (t) => `${t} Dokumente` }}
+          locale={{ emptyText: 'Keine Einträge vorhanden' }}
         />
-        
+
         <DocumentEditModal
             documentId={selectedDoc?.id || null}
             document={selectedDoc}
@@ -136,7 +138,6 @@ export default function ManuellBearbeitenPage() {
             isPosteingang={false}
             hasNextDocument={data.length > 1}
         />
-      </div>
-    </ConfigProvider>
+    </div>
   );
 }