feat(spec58): 审批人解析组件 ReviewerResolver 与发起接线

- 新增 ReviewerResolver：USER:<userId> / COLLEGE_ROLE:<roleCode>，; 分隔多段取并集升序
- reviewer_rule 为空回退 review_user_id；按学院解析空集合抛 BusinessException，消息含学院名/层级/缺什么
- ReviewFlowStarterService 发起与驳回重提改由解析取人，解析为空不写任何节点
- ReviewFlow 增加 reviewerRule 字段；DeclareRecordMapper 增加 selectReviewContext（仅 4 张在跑表）

src/main/java/com/gxwebsoft/gxmu/entity/ReviewFlow.java

@@ -51,6 +51,9 @@ public class ReviewFlow implements Serializable {
 
     private Integer reviewUserId;
 
+    @ApiModelProperty(value = "审批人规则，;分隔：USER:<userId> / COLLEGE_ROLE:<roleCode>；为空回退 review_user_id")
+    private String reviewerRule;
+
     @TableField(exist = false)
     private List<ReviewFlow> flows;