Bug/customer invoice bug (#628)

* fix(supplier-invoices): self-assess reverse-charge VAT + link payments to vouchers

Reverse-charge supplier invoices now carry a per-item reverse_charge_rate (0.06/0.12/0.25). Under omvänd skattskyldighet the supplier charges 0% VAT, so the line vat_rate stays 0 and the buyer self-assesses fiktiv moms at the statutory rate. Centralizes rate resolution (resolveReverseChargeRate) and the ruta 20-24 basis-account guard (isReverseChargeBasisAccount) in vat-entries so the booking engine and review-dialog preview can no longer drift.

Adds the link_supplier_invoice_voucher pending operation: mark a leverantorsfaktura paid by linking an existing posted verifikat that debits 2440, with no new journal entry. Exposes find-candidates/link MCP tools and the bulk-reconcile helper, scoped under suppliers:read/write.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(vat): report yearly VAT over the rakenskapsar, not the calendar year

Annual VAT (helarsmoms) is filed per beskattningsar/rakenskapsar (SFL 26 kap), which can be extended or shortened up to 18 months. The previous Jan-Dec calendar span silently dropped part of an extended first year. calculateVatDeclaration now accepts a fiscalPeriodId and resolves the period's actual bounds for yearly; monthly/quarterly stay calendar. The reports UI passes the selected fiscal period, defaults the periodicity from the company's moms_period setting, and carries the period into the ruta drill-down. full-archive export threads the period id through too.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(migration): resolve supplier invoice status from payment amounts

The provider's lifecycle status and its payment status are computed independently upstream and can contradict each other (e.g. a Fortnox invoice marked booked but fully paid). Both the arcim entity-mapper and the Fortnox mapper now let payment state win: fully paid -> paid, partial -> partially_paid, otherwise the mapped lifecycle status, with credit notes forced terminal. Balance is compared numerically (never strict === 0) so float drift or a residual ore resolves cleanly, and an absent Balance is treated as unpaid.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(enable-banking): only ingest booked transactions to stop re-import drift

Pending entries are skipped during sync: a pending row is unstable across syncs (a later 'synka nu' returns it still pending or finally booked, often with a different effective date). Because both the dedup external_id and the content-dedup key are date-derived, that drift minted a new id and re-imported a transaction that already existed - observed in production as the same amount+description landing twice with different dates. Gating the import set on a stable booking_date removes the drift at the source and leaves booked rows' ids byte-identical.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* chore(gitignore): ignore local SIE test fixtures

tests/fixtures/sie/ may contain real or scrubbed company data and must never be committed.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(invoice): handle errors during registration journal entry creation and ensure invoice rollback
feat(tests): add test for reverse charge rate handling on supplier invoice line items
feat(fortnox): ensure paid status reflects zero balance for fully paid invoices
chore(migrations): add reverse_charge_rate to supplier_invoice_items and backfill link_supplier_invoice_voucher

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/pending-operations/commit.ts

@@ -40,6 +40,7 @@ import {
   createSupplierInvoiceRegistrationEntry,
 } from '@/lib/bookkeeping/supplier-invoice-entries'
 import { linkInvoiceToVoucher } from '@/lib/invoices/voucher-matching'
+import { linkSupplierInvoiceToVoucher } from '@/lib/invoices/supplier-voucher-matching'
 import { linkTransactionToJournalEntry } from '@/lib/transactions/link-journal-entry'
 import { getErrorEntry } from '@/lib/errors/structured-errors'
 import { parseSIEFile } from '@/lib/import/sie-parser'
@@ -1038,6 +1039,48 @@ async function commitLinkInvoiceVoucher(
   }
 }
 
+async function commitLinkSupplierInvoiceVoucher(
+  supabase: SupabaseClient,
+  userId: string,
+  companyId: string,
+  params: Record<string, unknown>
+): Promise<ExecutorResult> {
+  const supplierInvoiceId = params.supplier_invoice_id as string | undefined
+  const journalEntryId = params.journal_entry_id as string | undefined
+  const notes = (params.notes as string | undefined) ?? undefined
+
+  if (!supplierInvoiceId || !journalEntryId) {
+    return { error: 'supplier_invoice_id and journal_entry_id are required', status: 400 }
+  }
+
+  const outcome = await linkSupplierInvoiceToVoucher(supabase, userId, companyId, {
+    supplierInvoiceId,
+    journalEntryId,
+    notes,
+  })
+
+  if (!outcome.ok) {
+    const entry = getErrorEntry(outcome.code)
+    // 404/409 are auto-rejected by the dispatcher (the user can re-stage with
+    // adjusted inputs); 400 surfaces as a normal failure so the UI can explain.
+    return {
+      error: entry?.message_en ?? outcome.code,
+      status: entry?.httpStatus ?? 500,
+    }
+  }
+
+  return {
+    data: {
+      invoice_status: outcome.result.invoiceStatus,
+      paid_amount: outcome.result.paidAmount,
+      remaining_amount: outcome.result.remainingAmount,
+      payment_amount: outcome.result.paymentAmount,
+      payment_id: outcome.result.paymentId,
+      journal_entry_id: outcome.result.journalEntryId,
+    },
+  }
+}
+
 // ── Stream 1 Phase 1 + follow-up executors ───────────────────────
 
 async function commitClosePeriod(
@@ -1614,6 +1657,11 @@ async function commitCreateSupplierInvoiceFromInbox(
       vat_code: null,
       vat_rate: vatRate,
       vat_amount: vatAmt,
+      // For reverse charge the buyer self-assesses VAT; carry an explicit
+      // statutory rate when staged, else null (engine defaults to 25%).
+      reverse_charge_rate: reverseCharge
+        ? ([0.06, 0.12, 0.25].includes(Number(item.reverse_charge_rate)) ? Number(item.reverse_charge_rate) : null)
+        : null,
     }
   })
 
@@ -2909,6 +2957,9 @@ export async function commitPendingOperation(
       case 'link_invoice_voucher':
         result = await commitLinkInvoiceVoucher(supabase, userId, companyId, pendingOp.params)
         break
+      case 'link_supplier_invoice_voucher':
+        result = await commitLinkSupplierInvoiceVoucher(supabase, userId, companyId, pendingOp.params)
+        break
       case 'close_period':
         result = await commitClosePeriod(supabase, userId, companyId, pendingOp.params)
         break