feat(flow): 用户面四查询(todo/done/cc/my)支持 appKey 按应用筛选

工作台四页签加「按应用筛选」：controller 收可选 appKey，经 FlowQueryService
透传到分页查询；口径=办件定义归属 flw_def.app_key（join flw_instance→flw_def，
均多对一，不影响已办「一个办件一行」的去重与分页）。appKey 空串按不过滤处理
(emptyToNull)，避免清筛选后误成空列表。FlwCcRepository 抄送派生查询相应改
@Query 以支持 join 过滤；FlowEngineIT 两处调用补 null 实参。

门禁：mvn compile/test-compile ✓ + 非 DB 单测 44 例 ✓；本机无 MySQL(3306
未监听)，新 JPQL 未在真实库执行，FlowEngineIT/OapiFlowContractIT 待有库环境补跑

src/main/java/com/yunhai/flowcenter/service/FlowQueryService.java

@@ -50,8 +50,8 @@ public class FlowQueryService {
     private final FlowEngine flowEngine;
 
     public BasePageResult<FlowModels.InstanceItem> pageMy(Long schId, Integer submitterId,
-                                                          Integer status, Integer page, Integer size) {
-        Page<FlwInstance> p = instanceRepository.pageMy(schId, submitterId, status,
+                                                          Integer status, String appKey, Integer page, Integer size) {
+        Page<FlwInstance> p = instanceRepository.pageMy(schId, submitterId, status, emptyToNull(appKey),
                 PageRequest.of(normPage(page), normSize(size)));
         return toResult(p.getTotalElements(), p.getContent().stream().map(this::toInstanceItem)
                 .collect(Collectors.toList()), page, size);
@@ -59,8 +59,8 @@ public class FlowQueryService {
 
     /** 抄送我的（NOTIFY 落库行，sent_time 倒序；知会不占待办，独立于 todo/done 口径） */
     public BasePageResult<FlowModels.CcItem> pageCc(Long schId, Integer userId,
-                                                    Integer page, Integer size) {
-        Page<FlwCc> p = ccRepository.findBySchIdAndUserIdOrderBySentTimeDesc(schId, userId,
+                                                    String appKey, Integer page, Integer size) {
+        Page<FlwCc> p = ccRepository.pageCc(schId, userId, emptyToNull(appKey),
                 PageRequest.of(normPage(page), normSize(size)));
         List<FlowModels.CcItem> items = p.getContent().stream()
                 .map(this::toCcItem).collect(Collectors.toList());
@@ -92,9 +92,9 @@ public class FlowQueryService {
         }
     }
 
-    public BasePageResult<FlowModels.TaskItem> pageTodo(Long schId, Integer assigneeId,
+    public BasePageResult<FlowModels.TaskItem> pageTodo(Long schId, Integer assigneeId, String appKey,
                                                         Integer page, Integer size) {
-        Page<FlwTask> p = taskRepository.pageTodo(schId, assigneeId,
+        Page<FlwTask> p = taskRepository.pageTodo(schId, assigneeId, emptyToNull(appKey),
                 PageRequest.of(normPage(page), normSize(size)));
         List<FlowModels.TaskItem> items = p.getContent().stream()
                 .map(this::toTaskItem).collect(Collectors.toList());
@@ -103,10 +103,10 @@ public class FlowQueryService {
     }
 
     /** 已办：一个办件一行（保留本人最后办理的那条），并回填累计办理次数 */
-    public BasePageResult<FlowModels.TaskItem> pageDone(Long schId, Integer assigneeId,
+    public BasePageResult<FlowModels.TaskItem> pageDone(Long schId, Integer assigneeId, String appKey,
                                                         Integer page, Integer size) {
         List<Integer> handled = FlwEnums.TaskStatus.handledCodes();
-        Page<FlwTask> p = taskRepository.pageDone(schId, assigneeId, handled,
+        Page<FlwTask> p = taskRepository.pageDone(schId, assigneeId, handled, emptyToNull(appKey),
                 PageRequest.of(normPage(page), normSize(size)));
         List<FlowModels.TaskItem> items = p.getContent().stream()
                 .map(this::toTaskItem).collect(Collectors.toList());
@@ -522,6 +522,11 @@ public class FlowQueryService {
         return page == null || page < 1 ? 0 : page - 1;
     }
 
+    /** 空串按「不过滤」处理（前端清筛选可能传空值，避免误筛成空列表） */
+    private static String emptyToNull(String s) {
+        return s == null || s.trim().isEmpty() ? null : s.trim();
+    }
+
     private static int normSize(Integer size) {
         return size == null || size < 1 || size > 100 ? 10 : size;
     }