feat(workshop): vehicles must be assigned to a customer

- Added customer_id column to fleet_vehicles with FK to customers.

- Enforced customer_id on create_vehicle endpoints (workshop and fleet).

- New vehicle modal now requires a selected customer and stores customer_id.

- Migration v4.13 applied to all tenants.

pos/templates/workshop.html

@@ -15,7 +15,7 @@
   <meta name="theme-color" content="#F5A623" />
   <link rel="shortcut icon" type="image/png" href="/pos/static/pwa/icon-192.png" />
 
-  <link rel="stylesheet" href="/pos/static/css/workshop.css?v=40">
+  <link rel="stylesheet" href="/pos/static/css/workshop.css?v=41">
   <style>
     .so-notes-grid { display: grid; grid-template-columns: 120px 1fr; gap: var(--space-2); align-items: start; }
     .so-notes-grid .form-label { margin: 0; padding-top: var(--space-2); }
@@ -372,8 +372,9 @@
           <input class="form-input" id="nvColor" placeholder="Ej. Blanco" />
         </div>
         <div class="form-field form-field--span2">
-          <label class="form-label" for="nvOwner">Due&ntilde;o</label>
-          <input class="form-input" id="nvOwner" placeholder="Nombre del due&ntilde;o" />
+          <label class="form-label" for="nvCustomerName">Cliente *</label>
+          <input type="hidden" id="nvCustomerId" />
+          <input class="form-input" id="nvCustomerName" readonly placeholder="Selecciona un cliente en la orden" />
         </div>
       </form>
     </div>
@@ -486,7 +487,7 @@
 <script src="/pos/static/js/pos-utils.js?v=33" defer></script>
 <script src="/pos/static/js/sidebar.js?v=36" defer></script>
 <script src="/pos/static/js/offline-banner.js" defer></script>
-<script src="/pos/static/js/workshop.js?v=40" defer></script>
+<script src="/pos/static/js/workshop.js?v=41" 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>
 <script src="/pos/static/js/chat.js" defer></script>