Fix/build (#1041)

* fix(bookkeeping): harden correction account changes

* feat(tax): enhance tax deadline generation with new settings and filing methods

- Added new company settings: tax_turnover_over_40m, vat_has_eu_trade, vat_filing_method, periodisk_sammanstallning_enabled, and periodisk_sammanstallning_filing_method.
- Updated deadline generation logic to accommodate new settings affecting VAT and employer declaration deadlines.
- Implemented tests for new functionality, ensuring that completed obligations are preserved and not replaced by new pending rows.
- Introduced a cron job to backfill missing tax deadlines for companies with settings but no upcoming deadlines.
- Updated API routes for generating tax deadlines and handling cron jobs.
- Modified database schema to include new columns for tax filing profiles and constraints for filing methods.

* fix(invoices): record credit note reconciliation guard

* fix(tax): correct automatic deadline settings

* fix(tax): key AGI deadline to VAT taxable base and add storforetag payment deadline

The 26th filing day for the skattedeklaration (AGI and VAT together) hinges
on one statutory measure, a VAT taxable base above SEK 40 million (SFL 26
kap.), not a separate employer turnover. Drop employer_turnover_over_40m and
derive the AGI schedule from vat_registered plus vat_taxable_base_over_40m,
so a non-VAT-reporting employer is never shown the 26th when its binding
date is the 12th.

Also:
- add a skatteinbetalning deadline row (12th, 17 January) for storforetag,
  whose deducted tax and employer contributions are due before the 26th
  filing date
- normalize legally incoherent over-40m flag combinations to the earlier
  small-company schedule in a follow-up migration
- replace hardcoded 27 December dates with the banking-day adjustment
- extend the 40m help text to cover the SKV-decided early filing election
  and the payment-still-on-the-12th rule
- document the regeneration race repaired by the daily backfill cron

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* feat(migrations): add AGI and VAT filing logic with employer column removal

* feat(settings): implement VAT registration logic and update related flags; enhance deadline handling

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

types/index.ts

@@ -121,6 +121,7 @@ export type AccountingMethod = 'accrual' | 'cash'
 
 // Moms reporting period
 export type MomsPeriod = 'monthly' | 'quarterly' | 'yearly'
+export type TaxFilingMethod = 'electronic' | 'paper'
 
 // Reconciliation method
 export type ReconciliationMethod = 'auto_exact' | 'auto_date_range' | 'auto_reference' | 'auto_fuzzy' | 'manual'
@@ -226,6 +227,11 @@ export interface CompanySettings {
   vat_number: string | null
   moms_period: MomsPeriod | null
   periodisk_sammanstallning_period: 'monthly' | 'quarterly'
+  vat_taxable_base_over_40m: boolean
+  vat_has_eu_trade: boolean
+  vat_filing_method: TaxFilingMethod
+  periodisk_sammanstallning_enabled: boolean
+  periodisk_sammanstallning_filing_method: TaxFilingMethod
 
   // Tax contact (SKV-filings, periodisk sammanställning, AGI, etc.)
   tax_contact_name: string | null
@@ -2155,6 +2161,7 @@ export type TaxDeadlineType =
   | 'moms_yearly'
   | 'f_skatt'
   | 'arbetsgivardeklaration'
+  | 'skatteinbetalning'
   | 'inkomstdeklaration_ef'
   | 'inkomstdeklaration_ab'
   | 'arsredovisning'
@@ -2329,6 +2336,7 @@ export const TAX_DEADLINE_TYPE_LABELS: Record<TaxDeadlineType, string> = {
   moms_yearly: 'Momsdeklaration (år)',
   f_skatt: 'F-skatt',
   arbetsgivardeklaration: 'Arbetsgivardeklaration',
+  skatteinbetalning: 'Skatteinbetalning (storföretag)',
   inkomstdeklaration_ef: 'Inkomstdeklaration EF',
   inkomstdeklaration_ab: 'Inkomstdeklaration AB',
   arsredovisning: 'Årsredovisning',