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/templates/config.html

@@ -718,19 +718,48 @@
        MODALS
        ===================================================================== -->
 
-  <!-- Modal: Nueva Sucursal -->
+  <!-- Modal: Nueva / Editar Sucursal -->
   <div class="cfg-modal-overlay" id="modal-branch" style="display:none;">
-    <div class="cfg-modal">
+    <div class="cfg-modal" style="max-width:640px;">
       <div class="cfg-modal__header">
-        <h3 class="cfg-modal__title">Nueva Sucursal</h3>
+        <h3 class="cfg-modal__title" id="branch-modal-title">Nueva Sucursal</h3>
         <button class="cfg-modal__close" onclick="Config.closeModal('modal-branch')">&times;</button>
       </div>
       <div class="cfg-modal__body">
+        <input type="hidden" id="branch-id" value="" />
         <div class="form-grid">
           <div class="form-group form-group--full">
-            <label class="form-label">Nombre</label>
+            <label class="form-label">Nombre *</label>
             <input class="form-input" id="branch-name" type="text" placeholder="Ej. Sucursal Norte" />
           </div>
+          <div class="form-group">
+            <label class="form-label">RFC</label>
+            <input class="form-input" id="branch-rfc" type="text" placeholder="ABC010101ABC" maxlength="13" />
+          </div>
+          <div class="form-group">
+            <label class="form-label">Razon Social</label>
+            <input class="form-input" id="branch-razon" type="text" placeholder="Razon social fiscal" />
+          </div>
+          <div class="form-group">
+            <label class="form-label">Regimen Fiscal</label>
+            <input class="form-input" id="branch-regimen" type="text" placeholder="601" maxlength="10" />
+          </div>
+          <div class="form-group">
+            <label class="form-label">Codigo Postal</label>
+            <input class="form-input" id="branch-cp" type="text" placeholder="00000" maxlength="5" />
+          </div>
+          <div class="form-group">
+            <label class="form-label">Serie CFDI</label>
+            <input class="form-input" id="branch-serie" type="text" placeholder="A" maxlength="10" />
+          </div>
+          <div class="form-group">
+            <label class="form-label">Folio Inicial</label>
+            <input class="form-input" id="branch-folio" type="number" placeholder="1" />
+          </div>
+          <div class="form-group">
+            <label class="form-label">Licencia Fiscal</label>
+            <input class="form-input" id="branch-licencia" type="text" placeholder="Opcional" />
+          </div>
           <div class="form-group form-group--full">
             <label class="form-label">Direccion</label>
             <input class="form-input" id="branch-address" type="text" placeholder="Calle, Colonia, Ciudad" />
@@ -739,6 +768,20 @@
             <label class="form-label">Telefono</label>
             <input class="form-input" id="branch-phone" type="tel" placeholder="(55) 1234-5678" />
           </div>
+          <div class="form-group form-group--full">
+            <label class="form-check" style="display:flex;align-items:center;gap:8px;cursor:pointer;">
+              <input type="checkbox" id="branch-main" style="width:auto;" />
+              <span>Sucursal principal (datos fiscales por defecto)</span>
+            </label>
+          </div>
+          <div class="form-group form-group--full">
+            <label class="form-label">Certificado PEM (opcional)</label>
+            <textarea class="form-input" id="branch-cert" rows="3" placeholder="-----BEGIN CERTIFICATE-----"></textarea>
+          </div>
+          <div class="form-group form-group--full">
+            <label class="form-label">Llave PEM (opcional)</label>
+            <textarea class="form-input" id="branch-key" rows="3" placeholder="-----BEGIN PRIVATE KEY-----"></textarea>
+          </div>
         </div>
       </div>
       <div class="cfg-modal__footer">
@@ -808,7 +851,7 @@
   <script src="/pos/static/js/pos-utils.js?v=2" defer></script>
   <script src="/pos/static/js/sidebar.js" defer></script>
   <script src="/pos/static/js/kiosk.js" defer></script>
-  <script src="/pos/static/js/config.js?v=2" defer></script>
+  <script src="/pos/static/js/config.js?v=3" defer></script>
   <script src="/pos/static/js/sync-engine.js" defer></script>
   <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
   <script src="/pos/static/js/pwa-install.js" defer></script>