feat: transaction categorization UX improvements and description matching

Add journal entry preview, human-readable account names, auto-apply VAT,
fallback template suggestions, example prompts, invoice match comparison,
and batch result feedback. Also includes user-description-match extension,
describe/batch-describe API routes, improved AI categorization with multi-
suggestion support, and template embedding search.

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

components/extensions/general/UserDescriptionMatchWorkspace.tsx

@@ -0,0 +1,15 @@
+'use client'
+
+import type { WorkspaceComponentProps } from '@/lib/extensions/workspace-registry'
+import EmptyExtensionState from '@/components/extensions/shared/EmptyExtensionState'
+import { TextSearch } from 'lucide-react'
+
+export default function UserDescriptionMatchWorkspace({ userId }: WorkspaceComponentProps) {
+  return (
+    <EmptyExtensionState
+      title="Beskrivningsmatchning"
+      description="Beskriv transaktioner med egna ord vid kategorisering. Systemet lär sig automatiskt och applicerar på framtida transaktioner från samma leverantör."
+      icon={<TextSearch className="h-12 w-12 text-muted-foreground/40 mb-4" />}
+    />
+  )
+}