Fix Float16 vector query execution (#42)

* Initial plan

* Add Float16 vector type handling in query executor

Co-authored-by: 1yefuwang1 <18023393+1yefuwang1@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: 1yefuwang1 <18023393+1yefuwang1@users.noreply.github.com>

Author: Copilot

vectorlite/constraint.cpp

@@ -221,6 +221,20 @@ absl::StatusOr<QueryExecutor::QueryResult> QueryExecutor::Execute() const {
         VECTORLITE_ASSERT(space_.normalize);
         BF16Vector normalized_vector = quantized_vector.Normalize();
 
+        auto result = index_.searchKnnCloserFirst(
+            normalized_vector.data().data(), knn_param->k, rowid_filter.get());
+        return result;
+      } else if (space_.vector_type == VectorType::Float16) {
+        F16Vector quantized_vector = QuantizeToF16(knn_param->query_vector);
+
+        if (!space_.normalize) {
+          return index_.searchKnnCloserFirst(quantized_vector.data().data(),
+                                             knn_param->k, rowid_filter.get());
+        }
+
+        VECTORLITE_ASSERT(space_.normalize);
+        F16Vector normalized_vector = quantized_vector.Normalize();
+
         auto result = index_.searchKnnCloserFirst(
             normalized_vector.data().data(), knn_param->k, rowid_filter.get());
         return result;