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>

lib/extensions/loader.ts

@@ -7,6 +7,7 @@ import { neBilagaExtension } from '@/extensions/ne-bilaga'
 import { aiChatExtension } from '@/extensions/general/ai-chat'
 import { invoiceInboxExtension } from '@/extensions/general/invoice-inbox'
 import { calendarExtension } from '@/extensions/general/calendar'
+import { userDescriptionMatchExtension } from '@/extensions/general/user-description-match'
 import type { Extension } from './types'
 
 // ── Enable Banking (PSD2) — opt-in extension ───────────────────────────
@@ -30,6 +31,7 @@ const FIRST_PARTY_EXTENSIONS: Extension[] = [
   aiChatExtension,
   invoiceInboxExtension,
   calendarExtension,
+  userDescriptionMatchExtension,
   // enableBankingExtension,  // Uncomment to activate PSD2 bank sync
 ]