fix(buchhaltung): clean up tab labels, remove badge indicator, add session notification for pending transactions

frontend/src/pages/Buchhaltung.tsx

@@ -2,7 +2,6 @@ import React, { useState, useEffect } from 'react';
 import DashboardLayout from '../components/dashboard/DashboardLayout';
 import {
   Alert,
-  Badge,
   Box,
   Button,
   Card,
@@ -1252,7 +1251,7 @@ function TransaktionenTab({ haushaltsjahre, selectedJahrId, onJahrChange }: {
       <Box sx={{ borderBottom: 1, borderColor: 'divider', mb: 2 }}>
         <Tabs value={txSubTab} onChange={(_, v) => setTxSubTab(v)}>
           <Tab label="Offene Buchungen" />
-          <Tab label="Gebuchte Buchungen" />
+          <Tab label="Buchungen" />
           <Tab label="Wiederkehrende Buchungen" />
         </Tabs>
       </Box>
@@ -2091,13 +2090,6 @@ export default function Buchhaltung() {
     }
   }, [haushaltsjahre]);
 
-  const { data: pendingCount } = useQuery({
-    queryKey: ['buchhaltungPending', selectedJahrId],
-    queryFn: () => buchhaltungApi.getPendingCount(selectedJahrId || undefined),
-    enabled: !!selectedJahrId,
-    refetchInterval: 30000,
-  });
-
   return (
     <DashboardLayout>
       <Box sx={{ display: 'flex', alignItems: 'center', gap: 1, mb: 3 }}>
@@ -2105,7 +2097,7 @@ export default function Buchhaltung() {
       </Box>
       <Box sx={{ borderBottom: 1, borderColor: 'divider' }}>
         <Tabs value={tabValue} onChange={handleTabChange} variant="scrollable" scrollButtons="auto">
-          <Tab label={<Badge badgeContent={pendingCount || 0} color="warning" invisible={!pendingCount}><span>Transaktionen Übersicht</span></Badge>} />
+          <Tab label="Transaktionen" />
           <Tab label="Übersicht" />
           <Tab label="Konten" />
         </Tabs>

frontend/src/pages/Dashboard.tsx

@@ -47,6 +47,7 @@ import VikunjaMyTasksWidget from '../components/dashboard/VikunjaMyTasksWidget';
 import VikunjaQuickAddWidget from '../components/dashboard/VikunjaQuickAddWidget';
 import VikunjaOverdueNotifier from '../components/dashboard/VikunjaOverdueNotifier';
 import AtemschutzExpiryNotifier from '../components/dashboard/AtemschutzExpiryNotifier';
+import BuchhaltungPendingNotifier from '../components/dashboard/BuchhaltungPendingNotifier';
 import AdminStatusWidget from '../components/dashboard/AdminStatusWidget';
 import AnnouncementBanner from '../components/dashboard/AnnouncementBanner';
 import VehicleBookingQuickAddWidget from '../components/dashboard/VehicleBookingQuickAddWidget';
@@ -495,6 +496,7 @@ function Dashboard() {
     <DashboardLayout>
       <VikunjaOverdueNotifier />
       <AtemschutzExpiryNotifier />
+      <BuchhaltungPendingNotifier />
 
       <Container maxWidth={false} disableGutters>
         <DndContext