refactor: 积分系统拆分为独立 erp-points crate

- 新建 erp-points crate（8 Entity + account/product service + handler）
- 商品 CRUD 和账户管理完整实现，订单/签到/规则端点暂返回 501
- 注册到 workspace + erp-server 路由 /api/v1/points/*
- API 路径不变，前端无需修改

crates/erp-server/src/state.rs

@@ -122,3 +122,13 @@ impl FromRef<AppState> for erp_ai::AiState {
         state.ai_state.clone()
     }
 }
+
+/// Allow erp-points handlers to extract their required state.
+impl FromRef<AppState> for erp_points::PointsState {
+    fn from_ref(state: &AppState) -> Self {
+        Self {
+            db: state.db.clone(),
+            event_bus: state.event_bus.clone(),
+        }
+    }
+}