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/__tests__/sectors.test.ts

@@ -11,8 +11,8 @@ describe('sectors registry', () => {
     expect(SECTORS.length).toBe(6)
   })
 
-  it('should have 18 total extensions', () => {
-    expect(getAllExtensions().length).toBe(19)
+  it('should have 20 total extensions', () => {
+    expect(getAllExtensions().length).toBe(20)
   })
 
   it('should have unique slugs within each sector', () => {