feat: Fase 1-3 completas - precios proveedor, multi-sucursal, factura global

Fase 1: Lista de precios de proveedor
- Tabla supplier_catalog_prices en master DB
- Endpoints GET/POST/PUT/DELETE /supplier-catalog/prices
- Upload CSV/Excel de precios de proveedor
- Visualizacion de supplier_price en catalogo y POS

Fase 2: Multi-sucursal completo
- Migracion v4.0: inventory.branch_id=NULL, tabla inventory_stock
- Campos fiscales en branches (RFC, regimen, CP, serie CFDI, certificados)
- Trigger trg_update_inventory_stock para sincronizar stock por sucursal
- Backend config_bp.py con CRUD de sucursales fiscales
- Backend inventory_bp.py y pos_bp.py refactorizados para inventario compartido
- Backend invoicing_bp.py usa datos fiscales de la sucursal de la venta
- Frontend config.html/js con modal de sucursales expandido

Fase 3: Factura global mensual
- Migracion v4.1: tablas global_invoice_sales, sales.global_invoiced_at
- build_global_invoice_xml() con InformacionGlobal SAT-compliant
- Servicio global_invoice.py para agrupar ventas PUE <=000
- Endpoints POST/GET /global-invoice y /global-invoice/eligible-sales
- Frontend invoicing.html/js con boton y modal de factura global

pos/static/js/catalog.js

@@ -46,6 +46,11 @@
     var checkoutBtn   = document.getElementById('checkoutBtn');
     var cartFab       = document.getElementById('cartFab');
     var cartCloseBtn  = document.getElementById('cartCloseBtn');
+    // Supplier prices upload
+    var uploadPricesBtn  = document.getElementById('uploadPricesBtn');
+    var uploadPricesModal= document.getElementById('uploadPricesModal');
+    var uploadPricesFile = document.getElementById('uploadPricesFile');
+    var uploadPricesStatus=document.getElementById('uploadPricesStatus');
 
     // ─── Navigation State ───
     var nav = {
@@ -1053,6 +1058,7 @@
                     '</div>' +
                     '<div class="part-card__footer">' +
                     (p.local_price ? '<span class="part-card__price">$' + fmt(p.local_price) + '</span>' : '<span class="part-card__price" style="color:var(--color-text-muted);">Sin precio</span>') +
+                    (p.supplier_price ? '<span class="part-card__price" style="color:#2d7d46;font-size:0.85em;">Prov: $' + fmt(p.supplier_price) + '</span>' : '') +
                     stockBadge +
                     '</div>' +
                     '</article>';
@@ -2105,6 +2111,53 @@
         });
     }
 
+    // ─── Supplier prices upload ─────────────────────────────────────────────
+    function openUploadPricesModal() {
+        if (uploadPricesModal) uploadPricesModal.style.display = 'flex';
+        if (uploadPricesStatus) uploadPricesStatus.innerHTML = '';
+        if (uploadPricesFile) uploadPricesFile.value = '';
+    }
+    function closeUploadPricesModal() {
+        if (uploadPricesModal) uploadPricesModal.style.display = 'none';
+    }
+    async function submitUploadPrices() {
+        if (!uploadPricesFile || !uploadPricesFile.files || !uploadPricesFile.files[0]) {
+            if (uploadPricesStatus) uploadPricesStatus.innerHTML = '<span style="color:var(--color-error);">Selecciona un archivo primero.</span>';
+            return;
+        }
+        var form = new FormData();
+        form.append('file', uploadPricesFile.files[0]);
+        if (uploadPricesStatus) uploadPricesStatus.innerHTML = 'Subiendo...';
+        try {
+            var res = await fetch('/pos/api/supplier-catalog/prices/upload', {
+                method: 'POST',
+                headers: { 'Authorization': 'Bearer ' + token },
+                body: form
+            });
+            var data = await res.json();
+            if (res.ok && data.success) {
+                if (uploadPricesStatus) uploadPricesStatus.innerHTML = '<span style="color:var(--color-success);">✓ Precios actualizados: ' + data.processed + ' (insertados: ' + data.inserted + ', actualizados: ' + data.updated + ')</span>';
+                uploadPricesFile.value = '';
+            } else {
+                var msg = data.error || 'Error al subir precios';
+                var details = (data.details || []).join('<br>');
+                if (uploadPricesStatus) uploadPricesStatus.innerHTML = '<span style="color:var(--color-error);">' + esc(msg) + '</span>' + (details ? '<div style="margin-top:4px;font-size:0.9em;">' + details + '</div>' : '');
+            }
+        } catch (e) {
+            if (uploadPricesStatus) uploadPricesStatus.innerHTML = '<span style="color:var(--color-error);">Error de red: ' + esc(e.message) + '</span>';
+        }
+    }
+
+    function shouldShowUploadPricesButton() {
+        try {
+            var user = JSON.parse(localStorage.getItem('pos_employee') || '{}');
+            return user.role === 'owner' || user.role === 'admin';
+        } catch (e) { return false; }
+    }
+    if (uploadPricesBtn && shouldShowUploadPricesButton()) {
+        uploadPricesBtn.style.display = 'inline-flex';
+    }
+
     window.CatalogApp = {
         toggleCart: toggleCart,
         goToCheckout: goToCheckout,
@@ -2124,6 +2177,9 @@
         togglePlate: togglePlate,
         lookupPlate: lookupPlate,
         setMode: setCatalogMode,
+        openUploadPricesModal: openUploadPricesModal,
+        closeUploadPricesModal: closeUploadPricesModal,
+        submitUploadPrices: submitUploadPrices,
     };
 
     // ─── INIT ───