Carry actual flow state and freeze callback round identity

Local review candidate only. Explicitly selected inherited prerequisites and prior repair patches; unrelated WIP and independent MQ fixes are excluded. No push or deployment authorized.

src/main/java/com/yunhai/flowcenter/callback/CallbackDispatcher.java

@@ -120,6 +120,10 @@ public class CallbackDispatcher {
             if (event.getData() != null) {
                 data.putAll(event.getData());
             }
+            // 身份在事件发布线程中冻结，不能用 AFTER_COMMIT 重读到的新轮给旧事件重新贴标。
+            if (event.getRoundIdentity() != null) {
+                data.putAll(event.getRoundIdentity());
+            }
             payload.put("data", data);
             String payloadJson = objectMapper.writeValueAsString(payload);