Feat: Add German language support for agent template and various UI elements (#12830)

### What problem does this PR solve?

This PR updates and extends the german language support in the frontend.
Additionally two more elements are handled dynamically now. The
interactive Agent is also titled and described in german now.

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

Co-authored-by: Jakob <16180662+hauberj@users.noreply.github.com>

web/src/pages/home/application-card.tsx

@@ -1,6 +1,7 @@
 import { RAGFlowAvatar } from '@/components/ragflow-avatar';
 import { Card, CardContent } from '@/components/ui/card';
 import { formatDate } from '@/utils/date';
+import { t } from 'i18next';
 import { ChevronRight } from 'lucide-react';
 
 type ApplicationCardProps = {
@@ -50,7 +51,7 @@ export function SeeAllAppCard({ click }: SeeAllAppCardProps) {
   return (
     <Card className="w-full min-h-[76px] cursor-pointer" onClick={click}>
       <CardContent className="p-2.5 pt-1 w-full h-full flex items-center justify-center gap-1.5 text-text-secondary">
-        See All <ChevronRight className="size-4" />
+        {t('common.seeAll')} <ChevronRight className="size-4" />
       </CardContent>
     </Card>
   );