feat(accounting): supplier-country tax default + configurable default output VAT code

VAT supplier-country reclaim default:
- Migration 134 adds inbound_documents.supplier_country.
- categorizeInbound auto-derives tax_treatment via resolveTaxTreatment:
  explicit treatment wins; else country in the reclaim list → domestic,
  outside it → foreign_vat_non_reclaimable, unknown → domestic. Consumes the
  previously-stored-but-unused accounting_vat_reclaim_countries.
- Triage modal gains a Supplier country dropdown (saved via updateInbound).
  +5 unit tests for resolveTaxTreatment.

Configurable default output VAT code for new invoices:
- New accounting_default_output_vat_code setting (PUT wired; getSettings/type).
- Settings → Accounting dropdown to pick it.
- Invoice + quote editors seed their VAT picker (rate + code) from it on a
  blank new document — skipping edits/conversions, never clobbering a touched
  value. New docs no longer silently start at 0%.

i18n en + de.

backend/src/routes/adminSettings.js

@@ -258,6 +258,16 @@ router.put('/accounting', adminAuth, requirePermission('settings.edit'), async (
         setting_type: 'accounting',
       });
     }
+    // Default OUTPUT VAT code stamped onto NEW invoices/quotes (the editor
+    // seeds its VAT picker from it). Stored as the code string; '' clears it.
+    if (Object.prototype.hasOwnProperty.call(req.body, 'accounting_default_output_vat_code')) {
+      const code = String(req.body.accounting_default_output_vat_code || '').trim().slice(0, 16);
+      updates.push({
+        setting_key: 'accounting_default_output_vat_code',
+        setting_value: JSON.stringify(code),
+        setting_type: 'accounting',
+      });
+    }
     if (Object.prototype.hasOwnProperty.call(req.body, 'accounting_vat_reclaim_countries')) {
       const arr = Array.isArray(req.body.accounting_vat_reclaim_countries)
         ? req.body.accounting_vat_reclaim_countries

backend/src/services/expenseService.js

@@ -44,7 +44,8 @@ function toIsoDate(v) {
 
 // ── Accounting settings (app_settings, type 'accounting') ───────────────────
 async function getAccountingSettings() {
-  const keys = ['accounting_km_rate_minor', 'accounting_per_diem_rate_minor', 'accounting_require_proof'];
+  const keys = ['accounting_km_rate_minor', 'accounting_per_diem_rate_minor', 'accounting_require_proof',
+    'accounting_vat_reclaim_countries'];
   let rows = [];
   try {
     rows = await db('app_settings').whereIn('setting_key', keys).select('setting_key', 'setting_value');
@@ -59,9 +60,25 @@ async function getAccountingSettings() {
     kmRateMinor: Number.isFinite(Number(map.accounting_km_rate_minor)) ? Number(map.accounting_km_rate_minor) : 0,
     perDiemRateMinor: Number.isFinite(Number(map.accounting_per_diem_rate_minor)) ? Number(map.accounting_per_diem_rate_minor) : 0,
     requireProof: map.accounting_require_proof === true || map.accounting_require_proof === 1 || map.accounting_require_proof === '1',
+    vatReclaimCountries: Array.isArray(map.accounting_vat_reclaim_countries)
+      ? map.accounting_vat_reclaim_countries.map((c) => String(c || '').toUpperCase()) : [],
   };
 }
 
+/**
+ * Default tax treatment from the supplier country: explicit payload wins; else
+ * a country in the reclaim list (typically CH / LI) is `domestic` (input VAT
+ * reclaimable), an out-of-list country is `foreign_vat_non_reclaimable`, and an
+ * unknown country falls back to `domestic`. reverse_charge / import_goods stay
+ * admin-set (can't be auto-detected).
+ */
+function resolveTaxTreatment(payloadTreatment, supplierCountry, reclaimCountries) {
+  if (TAX_TREATMENTS.includes(payloadTreatment)) return payloadTreatment;
+  const cc = String(supplierCountry || '').toUpperCase();
+  if (!cc) return 'domestic';
+  return reclaimCountries.includes(cc) ? 'domestic' : 'foreign_vat_non_reclaimable';
+}
+
 // ── Incoming invoices (inbound_documents) ───────────────────────────────────
 function transformInbound(row) {
   if (!row) return null;
@@ -102,6 +119,7 @@ function transformInbound(row) {
     customerAccountId: row.customer_account_id || null,
     customerName: row.customer_display_name || row.customer_company_name || null,
     customerEmail: row.customer_email || null,
+    supplierCountry: row.supplier_country || null,
     note: row.note || null,
     // supplier payment (paid on the incoming invoice itself)
     supplierPaid: !!row.supplier_paid,
@@ -210,7 +228,7 @@ const INBOUND_EDITABLE = {
   supplierName: 'supplier_name', invoiceNumber: 'invoice_number', invoiceDate: 'invoice_date',
   dueDate: 'due_date', currency: 'currency', netAmountMinor: 'net_amount_minor',
   vatAmountMinor: 'vat_amount_minor', totalAmountMinor: 'total_amount_minor', iban: 'iban',
-  paymentReference: 'payment_reference', note: 'note',
+  paymentReference: 'payment_reference', note: 'note', supplierCountry: 'supplier_country',
 };
 
 async function updateInbound(id, payload, adminId) {
@@ -369,6 +387,10 @@ async function categorizeInbound(id, payload, adminId) {
     throw new AppError('customerAccountId is required to re-bill', 400, 'CUSTOMER_REQUIRED');
   }
 
+  // Reclaim-country list for the tax-treatment auto-default (loaded before the
+  // transaction — a global-db read).
+  const { vatReclaimCountries } = await getAccountingSettings();
+
   let billedInvoiceId = null;
   await db.transaction(async (trx) => {
     const row = await trx('inbound_documents').where({ id }).first();
@@ -390,7 +412,8 @@ async function categorizeInbound(id, payload, adminId) {
 
     const patch = {
       disposition,
-      tax_treatment: TAX_TREATMENTS.includes(payload.taxTreatment) ? payload.taxTreatment : 'domestic',
+      // Explicit treatment wins; else auto-default from the supplier country.
+      tax_treatment: resolveTaxTreatment(payload.taxTreatment, doc.supplierCountry, vatReclaimCountries),
       event_id: BOOKING_DISPOSITIONS.includes(disposition) ? (payload.eventId || null) : null,
       category_id: disposition === 'eigener_aufwand' ? (payload.categoryId || null) : null,
       customer_account_id: customerAccountId,
@@ -797,5 +820,5 @@ module.exports = {
   PAYMENT_METHODS,
   EXPENSE_KINDS,
   // unit-test surface
-  _internal: { computeMarkupMinor, resolveMarkup, computeExpenseAmount, buildExpenseInsert, transformExpense, transformInbound, buildInboundLineItem, isInvoiceMutable },
+  _internal: { computeMarkupMinor, resolveMarkup, computeExpenseAmount, buildExpenseInsert, transformExpense, transformInbound, buildInboundLineItem, isInvoiceMutable, resolveTaxTreatment },
 };