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/layouts/AppLayout.tsx

@@ -125,7 +125,7 @@ export default function AppLayout() {
         }}
       >
         {/* Logo / Collapse-Toggle */}
-        <div
+        <button
           onClick={() => setCollapsed(!collapsed)}
           style={{
             height: 56,
@@ -134,7 +134,11 @@ export default function AppLayout() {
             justifyContent: 'center',
             cursor: 'pointer',
             userSelect: 'none',
+            border: 'none',
             borderBottom: `1px solid ${isDark ? 'rgba(255,255,255,0.08)' : '#e2e4ea'}`,
+            background: 'transparent',
+            width: '100%',
+            padding: 0,
             transition: 'background 0.2s',
           }}
           onMouseEnter={(e) => (e.currentTarget.style.background = isDark ? 'rgba(255,255,255,0.04)' : 'rgba(0,0,0,0.02)')}
@@ -143,7 +147,7 @@ export default function AppLayout() {
           <Text strong style={{ color: logoColor, fontSize: collapsed ? 14 : 18, transition: 'font-size 0.2s' }}>
             {collapsed ? 'PM' : 'Paperless'}
           </Text>
-        </div>
+        </button>
 
         {/* Navigation Menu */}
         <Menu
@@ -179,7 +183,7 @@ export default function AppLayout() {
         >
           {/* Theme Toggle */}
           <Tooltip title={isDark ? 'Light Mode' : 'Dark Mode'} placement="right">
-            <div
+            <button
               onClick={toggleTheme}
               style={{
                 display: 'flex',
@@ -190,14 +194,17 @@ export default function AppLayout() {
                 cursor: 'pointer',
                 color: subtleColor,
                 justifyContent: collapsed ? 'center' : 'flex-start',
-                transition: 'all 0.2s',
+                border: 'none',
+                background: 'transparent',
+                width: '100%',
+                transition: 'background 0.2s',
               }}
               onMouseEnter={(e) => (e.currentTarget.style.background = isDark ? 'rgba(255,255,255,0.08)' : '#eef1f8')}
               onMouseLeave={(e) => (e.currentTarget.style.background = 'transparent')}
             >
               {isDark ? <SunOutlined style={{ fontSize: 16 }} /> : <MoonOutlined style={{ fontSize: 16 }} />}
               {!collapsed && <Text style={{ color: subtleColor, fontSize: 13 }}>{isDark ? 'Light Mode' : 'Dark Mode'}</Text>}
-            </div>
+            </button>
           </Tooltip>
 
           {/* User Menu */}

paperless-frontend/src/pages/InboxDetailPage.tsx

@@ -1176,7 +1176,7 @@ export default function InboxDetailPage() {
           <Button icon={<ArrowLeftOutlined />} onClick={() => navigate('/inbox')}>
             Zurück
           </Button>
-          <Title level={4} style={{ margin: 0 }}>
+          <Title level={3} style={{ margin: 0 }}>
             {file.name}
           </Title>
           <SourceTag source={file.source} />

paperless-frontend/src/pages/InboxPage.tsx

@@ -387,7 +387,7 @@ export default function InboxPage() {
             onChange={(e) => setSearch(e.target.value)}
             allowClear
           />
-          <Button icon={<ReloadOutlined />} onClick={load}>
+          <Button icon={<ReloadOutlined />} onClick={load} loading={loading}>
             Aktualisieren
           </Button>
           <Popconfirm

paperless-frontend/src/pages/MailDetailPage.tsx

@@ -1,7 +1,7 @@
 import { useEffect, useState } from 'react';
 import { useParams, useNavigate } from 'react-router-dom';
 import {
-  Card, Button, Space, Spin, Tag, Typography, Table, message, Empty, Popconfirm
+  Card, Button, Space, Spin, Tag, Typography, Table, message, Empty, Popconfirm, theme
 } from 'antd';
 import { ArrowLeftOutlined, FileTextOutlined, CloseCircleOutlined, LinkOutlined } from '@ant-design/icons';
 import type { ColumnsType } from 'antd/es/table';
@@ -23,6 +23,7 @@ export default function MailDetailPage() {
   const [loading, setLoading] = useState(true);
   const [previewLoading, setPreviewLoading] = useState(false);
   const [wizardOpen, setWizardOpen] = useState(false);
+  const { token } = theme.useToken();
 
   useEffect(() => {
     if (!id) return;
@@ -208,7 +209,7 @@ export default function MailDetailPage() {
 
         {/* Rechte Seite: Anhänge + Vorschau */}
         <Card size="small" styles={{ body: { padding: 0, display: 'flex', flexDirection: 'column', height: 'calc(100vh - 200px)' } }}>
-          <div style={{ flex: '0 0 auto', borderBottom: '1px solid #303030', maxHeight: 240, overflow: 'auto' }}>
+          <div style={{ flex: '0 0 auto', borderBottom: `1px solid ${token.colorBorder}`, maxHeight: 240, overflow: 'auto' }}>
             <Table<EmailAttachment>
               columns={columns}
               dataSource={attachments}
@@ -223,7 +224,7 @@ export default function MailDetailPage() {
               locale={{ emptyText: <Empty description="Keine Anhänge" image={Empty.PRESENTED_IMAGE_SIMPLE} /> }}
             />
           </div>
-          <div style={{ flex: 1, minHeight: 0, background: '#1a1a2e' }}>
+          <div style={{ flex: 1, minHeight: 0, background: token.colorBgLayout }}>
             {previewLoading ? (
               <div style={{ display: 'flex', justifyContent: 'center', alignItems: 'center', height: '100%' }}>
                 <Spin />
@@ -240,7 +241,7 @@ export default function MailDetailPage() {
               )
             ) : (
               <div style={{ display: 'flex', justifyContent: 'center', alignItems: 'center', height: '100%', color: '#888' }}>
-                <Space vertical align="center">
+                <Space direction="vertical" align="center">
                   <FileTextOutlined style={{ fontSize: 48 }} />
                   <Text type="secondary">Kein Anhang ausgewählt</Text>
                 </Space>

paperless-frontend/src/pages/MailpostfachPage.tsx

@@ -219,6 +219,7 @@ export default function MailpostfachPage() {
           loading={loading}
           rowKey="Id"
           pagination={{ pageSize: 20, showSizeChanger: true, showTotal: (t) => `${t} E-Mails` }}
+          locale={{ emptyText: 'Keine Einträge vorhanden' }}
           onRow={(record) => ({
             onClick: () => navigate(`/mailpostfach/${record.Id}`),
             style: { cursor: 'pointer' },

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>
   );
 }

paperless-frontend/src/pages/PosteingangPage.tsx

@@ -1,7 +1,9 @@
 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';
 import { AuthImage } from '../utils/auth-resource';
 import { ReloadOutlined } from '@ant-design/icons';
+
+const { Title } = Typography;
 import dayjs from 'dayjs';
 import { posteingangApi } from '../api/posteingang';
 import type { PosteingangDocument } from '../api/posteingang';
@@ -98,7 +100,7 @@ export default function PosteingangPage() {
       render: (text: string) => dayjs(text).format('DD.MM.YYYY HH:mm'),
     },
     {
-      title: 'Aktion',
+      title: 'Aktionen',
       key: 'action',
       width: 150,
       render: (_: any, record: PosteingangDocument) => (
@@ -110,10 +112,9 @@ export default function PosteingangPage() {
   ];
 
   return (
-    <ConfigProvider>
-      <div style={{ padding: '0 24px 24px' }}>
-        <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginBottom: 16 }}>
-            <h2>Posteingang</h2>
+    <div>
+      <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginBottom: 16 }}>
+            <Title level={3} style={{ margin: 0 }}>Posteingang</Title>
             <Space>
                 <Tooltip title="Manuell aktualisieren">
                     <Button icon={<ReloadOutlined />} onClick={fetchData} loading={loading} />
@@ -125,9 +126,10 @@ export default function PosteingangPage() {
           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}
@@ -137,7 +139,6 @@ export default function PosteingangPage() {
             isPosteingang={true}
             hasNextDocument={data.length > 1}
         />
-      </div>
-    </ConfigProvider>
+    </div>
   );
 }

paperless-frontend/src/pages/TaskLogPage.tsx

@@ -161,6 +161,7 @@ export default function TaskLogPage() {
           rowKey="TaskId"
           loading={loading}
           pagination={{ pageSize: 20 }}
+          locale={{ emptyText: 'Keine Einträge vorhanden' }}
         />
       </div>
     </ConfigProvider>