feat: merge user-description-match into ai-categorization with AI-powered description analysis

Consolidate the standalone user-description-match extension into ai-categorization,
adding an AI description analyzer that provides account/VAT suggestions alongside
template matching. The describe transaction dialog now shows AI suggestions with
confidence scores and supports both template-based and AI-based booking.

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

lib/extensions/__tests__/sectors.test.ts

@@ -48,8 +48,8 @@ describe('sectors registry', () => {
     expect(SECTORS.length).toBe(1)
   })
 
-  it('should have 9 total extensions', () => {
-    expect(getAllExtensions().length).toBe(9)
+  it('should have 8 total extensions', () => {
+    expect(getAllExtensions().length).toBe(8)
   })
 
   it('should have unique slugs within each sector', () => {
@@ -93,7 +93,7 @@ describe('sectors registry', () => {
 
   it('getExtensionsBySector returns extensions for a sector', () => {
     const extensions = getExtensionsBySector('general')
-    expect(extensions.length).toBe(9)
+    expect(extensions.length).toBe(8)
   })
 
   it('all extensions have required fields', () => {