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/blueprints/config_bp.py

@@ -312,6 +312,35 @@ def update_employee(emp_id):
     return jsonify({'ok': True, 'message': 'Employee updated'})
 
 
+@config_bp.route('/employees/<int:emp_id>', methods=['DELETE'])
+@require_auth('config.edit')
+def delete_employee(emp_id):
+    """Soft-delete (deactivate) an employee. Owners cannot be deleted via UI
+    to prevent locking out the tenant; use direct DB access if really needed."""
+    conn = get_tenant_conn(g.tenant_id)
+    cur = conn.cursor()
+
+    cur.execute("SELECT role FROM employees WHERE id = %s", (emp_id,))
+    row = cur.fetchone()
+    if not row:
+        cur.close(); conn.close()
+        return jsonify({'error': 'Employee not found'}), 404
+
+    if row[0] == 'owner':
+        cur.close(); conn.close()
+        return jsonify({'error': 'No se puede eliminar una cuenta de dueno'}), 403
+
+    cur.execute("UPDATE employees SET is_active = false WHERE id = %s", (emp_id,))
+
+    from services.audit import log_action
+    log_action(conn, 'EMPLOYEE_DEACTIVATE', 'employee', emp_id)
+
+    conn.commit()
+    cur.close()
+    conn.close()
+    return jsonify({'ok': True, 'message': 'Employee deactivated'})
+
+
 @config_bp.route('/currency', methods=['GET'])
 @require_auth()
 def get_currency():