Fix Java and Python CI failures from the Dataset Specs merge

- Java: upstream #2774 added FromSerializedBuilder.withOutputDataset(
  DeserializeDataset), but this branch renamed DeserializeDataset to
  DenseOwningDataset. Update the remaining references in CagraIndex,
  the java22 CagraIndexImpl and CagraIndexDeprecatedBuilderIT.
- Python: common/dataset.pxd cimported cuvsKMeansType from
  cuvs.cluster.kmeans.kmeans, which imports that module when
  common.dataset initializes. That loops through cuvs.cluster ->
  neighbors -> cagra back into the half-initialized common.dataset
  (ImportError: cannot import name make_device_padded_dataset). Declare
  the enum locally from cuvs/cluster/kmeans.h instead.

Verification
- Full cuvs Python suite on GPU against a local libcuvs build:
  16663 passed, 168 skipped, 2 xfailed.
- Java not compiled locally (no JDK 22 or jextract).

Author: HowardHuang1

fern/pages/java_api/java-api-com-nvidia-cuvs-cagraindex.md

@@ -679,7 +679,7 @@ default FromSerializedBuilder fromSerialized(InputStream inputStream)
 Loads an index written by `CagraIndex#serialize(OutputStream)`, with its graph and
 dataset. `FromSerializedBuilder#build()` reads `inputStream` to its end, but
 closing it is left to the caller. The index owns the loaded dataset unless
-`FromSerializedBuilder#withOutputDataset(DeserializeDataset)` hands it to the caller.
+`FromSerializedBuilder#withOutputDataset(DenseOwningDataset)` hands it to the caller.
 
 **Parameters**
 
@@ -727,7 +727,7 @@ deserialization. The concrete output type must match the dataset layout stored i
 serialized index. Keep `outDataset` alive while the built index is in use. Unlike
 `#fromSerialized(InputStream)`, `#build()` closes `inputStream`.
 
-**Deprecated:** Use `#fromSerialized(InputStream)` and `FromSerializedBuilder#withOutputDataset(DeserializeDataset)`.
+**Deprecated:** Use `#fromSerialized(InputStream)` and `FromSerializedBuilder#withOutputDataset(DenseOwningDataset)`.
 
 **Parameters**
 
@@ -1027,7 +1027,7 @@ _Source: `java/cuvs-java/src/main/java/com/nvidia/cuvs/CagraIndex.java:727`_
 ### withOutputDataset
 
 ```java
-FromSerializedBuilder withOutputDataset(DeserializeDataset outDataset)
+FromSerializedBuilder withOutputDataset(DenseOwningDataset outDataset)
 ```
 
 Hands the loaded dataset to the caller instead of the index. `outDataset` must be

java/cuvs-java/src/main/java/com/nvidia/cuvs/CagraIndex.java

@@ -509,7 +509,7 @@ default FromGraphBuilder fromGraph(
      * Loads an index written by {@link CagraIndex#serialize(OutputStream)}, with its graph and
      * dataset. {@link FromSerializedBuilder#build()} reads {@code inputStream} to its end, but
      * closing it is left to the caller. The index owns the loaded dataset unless
-     * {@link FromSerializedBuilder#withOutputDataset(DeserializeDataset)} hands it to the caller.
+     * {@link FromSerializedBuilder#withOutputDataset(DenseOwningDataset)} hands it to the caller.
      *
      * @param inputStream the serialized index
      * @return a builder for the optional inputs
@@ -539,7 +539,7 @@ default FromSerializedBuilder fromSerialized(InputStream inputStream) {
      * @param outDataset an empty {@link PaddedDataset} or {@link StandardDataset}
      * @return an instance of this Builder
      * @deprecated Use {@link #fromSerialized(InputStream)} and
-     *     {@link FromSerializedBuilder#withOutputDataset(DeserializeDataset)}.
+     *     {@link FromSerializedBuilder#withOutputDataset(DenseOwningDataset)}.
      */
     @Deprecated(since = "26.12", forRemoval = true)
     Builder from(InputStream inputStream, DenseOwningDataset outDataset);
@@ -743,7 +743,7 @@ interface FromSerializedBuilder {
      * @return this builder
      * @throws IllegalStateException if called more than once
      */
-    FromSerializedBuilder withOutputDataset(DeserializeDataset outDataset);
+    FromSerializedBuilder withOutputDataset(DenseOwningDataset outDataset);
 
     /**
      * Loads the index. A builder creates one index, so this can be called only once,

java/cuvs-java/src/main/java22/com/nvidia/cuvs/internal/CagraIndexImpl.java

@@ -1849,7 +1849,7 @@ public CagraIndex build() throws Throwable {
   private static final class FromSerializedBuilderImpl implements CagraIndex.FromSerializedBuilder {
     private final CuVSResources resources;
     private final InputStream inputStream;
-    private CagraIndex.DeserializeDataset outDataset;
+    private CagraIndex.DenseOwningDataset outDataset;
     private boolean built;
 
     FromSerializedBuilderImpl(CuVSResources resources, InputStream inputStream) {
@@ -1859,7 +1859,7 @@ private static final class FromSerializedBuilderImpl implements CagraIndex.FromS
 
     @Override
     public CagraIndex.FromSerializedBuilder withOutputDataset(
-        CagraIndex.DeserializeDataset outDataset) {
+        CagraIndex.DenseOwningDataset outDataset) {
       Objects.requireNonNull(outDataset, "outDataset");
       checkNotSet(this.outDataset, "withOutputDataset");
       this.outDataset = outDataset;

java/cuvs-java/src/test/java/com/nvidia/cuvs/CagraIndexDeprecatedBuilderIT.java

@@ -74,7 +74,7 @@ public void loadsASerializedIndex() throws Throwable {
         assertEquals(ROWS, loaded.size());
       }
       assertTrue(stream.closed);
-      try (CagraIndex.DeserializeDataset outDataset =
+      try (CagraIndex.DenseOwningDataset outDataset =
               padded ? new CagraIndex.PaddedDataset() : new CagraIndex.StandardDataset();
           CagraIndex loaded =
               CagraIndex.newBuilder(resources)

python/cuvs/cuvs/common/dataset.pxd

@@ -7,11 +7,18 @@
 from libc.stdint cimport uint32_t
 from libcpp cimport bool
 
-from cuvs.cluster.kmeans.kmeans cimport cuvsKMeansType
 from cuvs.common.c_api cimport cuvsError_t, cuvsResources_t
 from cuvs.common.cydlpack cimport DLDataType, DLManagedTensor
 
 
+# Declared here rather than cimported from cuvs.cluster.kmeans.kmeans: that cimport imports the
+# kmeans module when this one initializes, which loops back into cuvs.common through cagra.
+cdef extern from "cuvs/cluster/kmeans.h" nogil:
+    ctypedef enum cuvsKMeansType:
+        CUVS_KMEANS_TYPE_KMEANS
+        CUVS_KMEANS_TYPE_KMEANS_BALANCED
+
+
 cdef extern from "cuvs/preprocessing/quantize/pq.h" nogil:
     ctypedef struct cuvsProductQuantizerParams:
         uint32_t pq_bits