fix(query): load all fields by default in FT.HYBRID post-processing

When no specific return fields are configured, call loadAll() so that
document content is included in the FT.HYBRID response. Without this,
queries return matched document keys but with empty field values.

Author: bsbodden

core/src/main/java/com/redis/vl/query/HybridQuery.java

@@ -294,10 +294,12 @@ public FTHybridParams buildFTHybridParams() {
     // Build COMBINE clause
     Combiner combiner = buildCombiner();
 
-    // Build POST-PROCESSING clause
+    // Build POST-PROCESSING clause — LOAD fields so document content is returned in the response
     FTHybridPostProcessingParams.Builder postBuilder = FTHybridPostProcessingParams.builder();
     if (!returnFields.isEmpty()) {
       postBuilder.load(returnFields.toArray(new String[0]));
+    } else {
+      postBuilder.loadAll();
     }
     postBuilder.limit(Limit.of(0, numResults));