feat(config): agrega opcion para eliminar empleados

- Backend: nuevo endpoint DELETE /employees/<id> que desactiva (soft-delete).
  No permite eliminar cuentas de dueno.
- Frontend: boton Eliminar en la tabla de empleados con confirmacion.
- Exponer deleteEmployee en el modulo Config.

Tests: 35 passed

pos/static/js/config.js

@@ -298,7 +298,10 @@ const Config = (() => {
                 + '<td>' + escHtml(emp.branch_name || 'Todas') + '</td>'
                 + '<td>' + statusBadge + '</td>'
                 + '<td>' + (emp.max_discount_pct || 0) + '%</td>'
-                + '<td><button class="btn btn--ghost btn--sm" onclick="Config.editEmployee(' + emp.id + ')">Editar</button></td>'
+                + '<td>'
+                + '<button class="btn btn--ghost btn--sm" onclick="Config.editEmployee(' + emp.id + ')">Editar</button>'
+                + (emp.role !== 'owner' ? ' <button class="btn btn--danger btn--sm" onclick="Config.deleteEmployee(' + emp.id + ', \'' + escHtml(emp.name).replace(/\\/g, '\\\\').replace(/'/g, "\\'") + '\')">Eliminar</button>' : '')
+                + '</td>'
                 + '</tr>';
         });
 
@@ -362,6 +365,21 @@ const Config = (() => {
         return el ? el.value.trim() : '';
     }
 
+    async function deleteEmployee(empId, name) {
+        if (!confirm('¿Eliminar al empleado "' + name + '"? Esta accion lo desactiva.')) return;
+        try {
+            var res = await fetch(API + '/employees/' + empId, { method: 'DELETE', headers: headers() });
+            if (!res.ok) {
+                var err = await res.json().catch(function() { return { error: 'Error ' + res.status }; });
+                throw new Error(err.error || 'Error al eliminar');
+            }
+            toast('Empleado eliminado', 'ok');
+            loadEmployees();
+        } catch (e) {
+            toast(e.message, 'error');
+        }
+    }
+
     async function editEmployee(empId) {
         if (!checkAuth()) return;
         // Find the employee in the loaded data by re-fetching
@@ -1028,7 +1046,7 @@ const Config = (() => {
 
     return {
         init, setTheme, selectThemeOption, loadAllowedBrands, saveAllowedBrands,
-        loadBranches, loadEmployees, saveBranch, saveEmployee, editEmployee,
+        loadBranches, loadEmployees, saveBranch, saveEmployee, editEmployee, deleteEmployee,
         loadBusiness, saveBusiness, saveTaxParams, saveAll,
         loadCurrency, saveCurrency,
         loadVehicleCompatSource, saveVehicleCompatSource,