fix(firewall): Tab-Farben via ConfigProvider statt CSS-Override

AntD 6 CSS-in-JS überschreibt externe Styles — ConfigProvider mit
Tabs-Tokens ist der korrekte Weg: itemColor #475569, hover #1e293b,
active #1677ff, fontSize 13px, Padding 10px 16px.

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

management-ui/src/pages/Firewall/index.tsx

@@ -1,4 +1,4 @@
-import { Space, Tag, Tabs } from 'antd'
+import { ConfigProvider, Space, Tag, Tabs } from 'antd'
 import { CheckCircleOutlined, CloseCircleOutlined, FireOutlined, SafetyOutlined } from '@ant-design/icons'
 import { useTranslation } from 'react-i18next'
 import { useQuery } from '@tanstack/react-query'
@@ -125,11 +125,16 @@ export default function FirewallPage() {
         )}
       />
       <FirewallKPIStrip nftablesActive={nftables?.active} />
-      <Tabs
-        items={tabs}
-        defaultActiveKey="rules"
-        className="fw-tabs"
-      />
+      <ConfigProvider theme={{ components: { Tabs: {
+        itemColor: '#475569',
+        itemHoverColor: '#1e293b',
+        itemSelectedColor: '#1677ff',
+        inkBarColor: '#1677ff',
+        titleFontSize: 13,
+        horizontalItemPadding: '10px 16px',
+      }}}}>
+        <Tabs items={tabs} defaultActiveKey="rules" />
+      </ConfigProvider>
     </div>
   )
 }