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/Cargo.toml

@@ -30,6 +30,7 @@ erp-message.workspace = true
 erp-plugin.workspace = true
 erp-health.workspace = true
 erp-ai.workspace = true
+erp-points.workspace = true
 anyhow.workspace = true
 uuid.workspace = true
 chrono.workspace = true