Bug/document linking (#688)

* feat: enhance supplier invoice payment process and settings handling

- Implemented linking of invoice documents to journal entries for cash payments in the supplier invoice payment process.
- Refactored settings fetching logic to improve loading states and error handling across various settings components.
- Introduced a new SettingsLoadError component to handle cases where settings fetch fails or returns no data.
- Updated useSettings hook to manage loading and error states more effectively, allowing for retries on failure.
- Enhanced tests for supplier invoice creation to ensure document IDs are persisted correctly for cash method payments.

* feat(salary): enable monthly salary edits in draft runs and handle zero-total declarations

components/settings/SettingsLoadError.tsx

@@ -0,0 +1,24 @@
+'use client'
+
+import { useTranslations } from 'next-intl'
+import { AlertCircle } from 'lucide-react'
+import { Button } from '@/components/ui/button'
+
+/**
+ * Shown when a settings section's fetch settled without a row (or errored).
+ * Replaces the old behaviour where a null `settings` object left the loading
+ * skeleton on screen indefinitely — a settled fetch always resolves to either
+ * content or this retryable state.
+ */
+export function SettingsLoadError({ onRetry }: { onRetry: () => void }) {
+  const t = useTranslations('common')
+  return (
+    <div className="flex flex-col items-center justify-center gap-4 py-12 text-center">
+      <AlertCircle className="h-8 w-8 text-muted-foreground" aria-hidden />
+      <p className="text-sm text-muted-foreground">{t('load_error')}</p>
+      <Button variant="outline" size="sm" onClick={onRetry}>
+        {t('retry')}
+      </Button>
+    </div>
+  )
+}