Add need_prefix for r_vid, headvideoid, union_id

Offline FG encoding adds feature_name prefix for id_features with
need_prefix=true (default): CONCAT('r_vid_', value). Online Java
must match: "r_vid_12345", "headvideoid_67890", "union_id_abc".

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

recommend-server-service/src/main/java/com/tzld/piaoquan/recommend/server/service/rank/strategy/RankStrategy4RegionMergeModelV562.java

@@ -378,7 +378,7 @@ public class RankStrategy4RegionMergeModelV562 extends RankStrategy4RegionMergeM
 
                     Map<String, String> featureMapString = new HashMap<>(featureMapToString);
                     FeatureV6.putVideoStringFeatures("r", rankInfo, featureMapString);
-                    featureMapString.put("r@vid", vid);
+                    featureMapString.put("r@vid", "r_vid_" + vid);
                     FeatureV6.putProfileVideoCrossStringFeature(currentMs, userProfile, historyVideoMap, featureMapString);
                     FeatureV6.putUserNetworkSeqFeature(featureMapString, userNetworkSeqFeature, videoBaseInfoMap);
                     item.featureMapString = featureMapString;

recommend-server-service/src/main/java/com/tzld/piaoquan/recommend/server/service/rank/tansform/FeatureV6.java

@@ -749,8 +749,8 @@ public class FeatureV6 {
             featureMapToString.put("e1_name", creativeInfo.getOrDefault("name", ""));
         }
 
-        featureMapToString.put("union_id", Optional.ofNullable(param.getUnionId()).orElse(""));
-        featureMapToString.put("headvideoid", Optional.ofNullable(param.getHeadVid()).map(Object::toString).orElse("-1024"));
+        featureMapToString.put("union_id", "union_id_" + Optional.ofNullable(param.getUnionId()).orElse(""));
+        featureMapToString.put("headvideoid", "headvideoid_" + Optional.ofNullable(param.getHeadVid()).map(Object::toString).orElse("-1024"));
 
         String pageSource = param.getCurrentPageSource();
         if (StringUtils.endsWith(pageSource, "pages/user-videos-share")) {