feat(workshop): make brand/model required, plate optional, remove VIN

- create_vehicle endpoints now require make and model; plate is optional; VIN is no longer stored.

- Updated new-vehicle modal: removed VIN field, plate is optional, brand/model marked required.

pos/static/js/workshop.js

@@ -726,7 +726,6 @@ var Workshop = (function() {
         document.getElementById('nvCustomerName').value = customerName;
         document.getElementById('newVehicleModal').classList.add('is-open');
         document.getElementById('nvPlate').value = '';
-        document.getElementById('nvVIN').value = '';
         document.getElementById('nvMake').value = '';
         document.getElementById('nvModel').value = '';
         document.getElementById('nvYear').value = '';
@@ -743,10 +742,11 @@ var Workshop = (function() {
 
     async function saveNewVehicle() {
         var plate = document.getElementById('nvPlate').value.trim();
-        var vin = document.getElementById('nvVIN').value.trim();
+        var make = document.getElementById('nvMake').value.trim();
+        var model = document.getElementById('nvModel').value.trim();
         var customerId = parseInt(document.getElementById('nvCustomerId').value, 10) || null;
-        if (!plate && !vin) {
-            alert('Se requiere al menos placa o VIN');
+        if (!make || !model) {
+            alert('Marca y modelo son obligatorios');
             return;
         }
         if (!customerId) {
@@ -755,17 +755,16 @@ var Workshop = (function() {
         }
         var payload = {
             plate: plate,
-            vin: vin,
             customer_id: customerId,
-            make: document.getElementById('nvMake').value.trim() || null,
-            model: document.getElementById('nvModel').value.trim() || null,
+            make: make,
+            model: model,
             year: document.getElementById('nvYear').value ? parseInt(document.getElementById('nvYear').value, 10) : null,
             color: document.getElementById('nvColor').value.trim() || null,
             branch_id: (currentOrder ? currentOrder.branch_id : null) || (window.POS_USER ? window.POS_USER.branch_id : null)
         };
         try {
             var res = await api('POST', '/vehicles', payload);
-            var label = plate + (payload.make ? ' · ' + payload.make : '') + (payload.model ? ' ' + payload.model : '');
+            var label = [payload.make, payload.model, payload.year, plate].filter(Boolean).join(' · ');
             if (newVehicleContext === 'new') {
                 var sel = document.getElementById('noVehicle');
                 var opt = document.createElement('option');