Supp/invoice bfl errors (#390)

* feat(accounting): update accounting method validation and messaging for aktiebolag and enskild firma

* Remove AI subsystem and related code

- Deleted AI proposals and requests persistence logic from `lib/ai/proposals/persist.ts`.
- Removed re-validation logic for proposals in `lib/ai/proposals/re-validate.ts`.
- Cleaned up schemas related to AI flows in `lib/api/schemas.ts`.
- Removed AI-related fields from bookkeeping engine in `lib/bookkeeping/engine.ts`.
- Eliminated AI event types from `lib/events/types.ts`.
- Updated tests to reflect the removal of AI-related functionality in `lib/extensions/__tests__/sectors.test.ts`.
- Adjusted initialization logic in `lib/init.ts` to exclude AI proposal handler registration.
- Cleaned up transaction ingestion logic in `lib/transactions/ingest.ts` to remove AI flow checks.
- Updated helper functions in `tests/helpers.ts` to remove AI-related settings.
- Removed AI-related types and interfaces from `types/index.ts`.
- Added migration script to drop AI-related tables and settings from the database.

* fix(migrations): ensure foreign key constraint is dropped before removing AI tables

* feat(invoice-inbox): implement deterministic invoice field extraction and inbox provisioning

- Added `extract-invoice-fields.ts` for extracting fields from PDF invoices using regex and pdfjs-dist, replacing the previous AI classifier.
- Introduced `inbox-provisioning.ts` to manage company inbox addresses and rotation of inboxes using Supabase RPCs.
- Created `resend-inbound.ts` for handling inbound email events and attachments via the Resend API.
- Defined the extension manifest for the invoice inbox, specifying required environment variables and descriptions.
- Migrated database schema to remove AI-related columns and tighten the status enum in `invoice_inbox_items`.

* feat(invoice-inbox): remove AI-specific columns and tighten status enum

* fix(skattekonto): remove manual entry creation reference from transaction input

* fix(schemas): remove accounting method validation for aktiebolag in UpdateSettingsSchema

lib/extensions/__tests__/sectors.test.ts

@@ -48,8 +48,8 @@ describe('sectors registry', () => {
     expect(SECTORS.length).toBe(1)
   })
 
-  it('should have 13 total extensions', () => {
-    expect(getAllExtensions().length).toBe(13)
+  it('should have 11 total extensions', () => {
+    expect(getAllExtensions().length).toBe(11)
   })
 
   it('should have unique slugs within each sector', () => {
@@ -94,7 +94,7 @@ describe('sectors registry', () => {
 
   it('getExtensionsBySector returns extensions for a sector', () => {
     const extensions = getExtensionsBySector('general')
-    expect(extensions.length).toBe(13)
+    expect(extensions.length).toBe(11)
   })
 
   it('all extensions have required fields', () => {