Add newsletter #30655

Author: NamjaeChoi

modules/doc/content/newsletter/2026/2026_01.md

@@ -7,6 +7,10 @@ for a complete description of all MOOSE changes.
 
 ## MOOSE Improvements
 
+### UserObject and Postprocessor support in Kokkos-MOOSE
+
+Kokkos-MOOSE now supports GPU-based [UserObjects](syntax/KokkosUserObjects/index.md) and [Postprocessors](syntax/KokkosUserObjects/index.md#reducers). Kokkos-MOOSE postprocessors leverage the reducer concept of Kokkos and have substantially different interface from the original MOOSE postprocessors. The Kokkos-MOOSE `VectorPostprocessors` and `Reporters` will also adopt the same reducer interface and be added soon. See the linked document for details.
+
 ## MOOSE Modules Changes
 
 ## libMesh-level Changes