feat: remove Administration workspace — keep only Verwaltung + Suche

- Delete all ops page components (ReviewQueue, AIMonitoring, Governance,
  SourceMonitoring, ActivityTimeline, SignalPipeline)
- Remove OPERATIONS workspace from AppShell config, nav order, path detection
- Remove all /ops/* routes from App.tsx
- Remove WorkspaceType.OPERATIONS from allowedWorkspaces in authService,
  sessionStore, permissions
- Keep MarketIntelligence page (already moved to /supply/market-intelligence)

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

.claude/worktrees/agent-a82a3716/src/components/ui/ToastProvider.tsx

@@ -0,0 +1,33 @@
+import { Alert, Snackbar, Stack } from '@mui/material'
+import { useToastStore } from '../../stores/toastStore'
+
+export function ToastProvider() {
+  const { toasts, dismissToast } = useToastStore()
+
+  return (
+    <Stack
+      spacing={1}
+      sx={{ position: 'fixed', bottom: 24, left: '50%', transform: 'translateX(-50%)', zIndex: 9999, alignItems: 'center' }}
+    >
+      {toasts.map((toast) => (
+        <Snackbar
+          key={toast.id}
+          open
+          autoHideDuration={toast.duration ?? 4000}
+          onClose={() => dismissToast(toast.id)}
+          anchorOrigin={{ vertical: 'bottom', horizontal: 'center' }}
+          sx={{ position: 'relative', transform: 'none', left: 'auto', bottom: 'auto' }}
+        >
+          <Alert
+            onClose={() => dismissToast(toast.id)}
+            severity={toast.severity}
+            variant="filled"
+            sx={{ minWidth: 320, boxShadow: 3 }}
+          >
+            {toast.message}
+          </Alert>
+        </Snackbar>
+      ))}
+    </Stack>
+  )
+}