feat: add recharge workflow models and schema statuses

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/tests/test_pl_vehicle_recharge_workflow.py

@@ -0,0 +1,8 @@
+"""车辆充值审批工作流：状态常量与核心流转单元测试。"""
+from app.schemas.pl.vehicle_recharge import APPLY_STATUSES, NODE_ACTION_TYPES, RECHARGE_TYPES
+
+
+def test_apply_statuses_include_workflow_states():
+    assert {"draft", "in_approval", "rejected", "disbursed", "cancelled"} <= APPLY_STATUSES
+    assert {"approve", "disburse"} <= NODE_ACTION_TYPES
+    assert {"etc", "fuel"} <= RECHARGE_TYPES