fix(lammps): register Kokkos plugin styles (#5988)

## Summary

Backport `0004-register-lammps-kokkos-plugin-styles.patch` from
`conda-forge/deepmd-kit-feedstock@d02138263b0b30629fe28c68c8bcecc2b8644513`.

Runtime LAMMPS plugins do not consume the `PairStyle` declarations used
by the built-in package machinery, so explicitly register:

- `deepmd/kk`
- `deepmd/kk/device`
- `deepmd/kk/host`
- `dpa4spin/kk`
- `dpa4spin/kk/device`
- `dpa4spin/kk/host`

The newly registered Kokkos plugin styles are attributed to **Tiancheng
Li** via `plugin.author`.

## Validation

- Single-file change derived from the feedstock patch, with only the
requested author attribution adjusted.
- Existing non-Kokkos plugin author fields are unchanged.
- Split from #5985 so plugin registration can be reviewed independently.
- Full build/runtime validation is left to upstream CI.

Agent: ChatGPT
Model: GPT-5.6 Sol

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **New Features**
  - Added Kokkos-enabled support for DeepMD and DPA-4Spin pair styles.
- Added host and device runtime variants for improved compatibility
across supported execution environments.
- Registered additional pair-style aliases so these implementations can
be selected through standard runtime configuration.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

## Dependencies and follow-up validation

Merge order: corrected #5987, then #5989, then this PR. The Kokkos
registrations in this PR depend on the compatibility boundary from #5987
and the shared-runtime linkage from #5989.

Validated the combined changes with `DEEPMD_LAMMPS_KOKKOS=ON`,
`PKG_PLUGIN=ON`, and `PKG_KOKKOS=ON` against `stable_22Jul2025_update5`,
`patch_10Sep2025`, and `patch_20Aug2026`. In every build, `plugin load`
succeeded and `plugin list` reported all six aliases: `deepmd/kk`,
`deepmd/kk/device`, `deepmd/kk/host`, `dpa4spin/kk`,
`dpa4spin/kk/device`, and `dpa4spin/kk/host`.

Coding agent: Codex
Codex version: codex-cli 0.149.0
Model: gpt-5.6-sol
Reasoning effort: xhigh

Co-authored-by: OutisLi <137472077+OutisLi@users.noreply.github.com>

Author: njzjz-bot

source/lmp/plugin/deepmdplugin.cpp

@@ -7,6 +7,10 @@
 #include "deepmd_version.h"
 #include "fix_dplr.h"
 #include "lammpsplugin.h"
+#ifdef LMP_KOKKOS
+#include "pair_deepmd_kokkos.h"
+#include "pair_dpa4spin_kokkos.h"
+#endif
 #include "pair_deepmd.h"
 #include "pair_deepspin.h"
 #include "version.h"
@@ -19,6 +23,23 @@ using namespace LAMMPS_NS;
 static Pair* pairdeepmd(LAMMPS* lmp) { return new PairDeepMD(lmp); }
 static Pair* pairdeepspin(LAMMPS* lmp) { return new PairDeepSpin(lmp); }
 
+#ifdef LMP_KOKKOS
+// Runtime plugins do not consume the PairStyle declarations used by LAMMPS'
+// built-in package machinery, so register each Kokkos alias explicitly.
+static Pair* pairdeepmdkokkosdevice(LAMMPS* lmp) {
+  return new PairDeepMDKokkos<LMPDeviceType>(lmp);
+}
+static Pair* pairdeepmdkokkoshost(LAMMPS* lmp) {
+  return new PairDeepMDKokkos<LMPHostType>(lmp);
+}
+static Pair* pairdpa4spinkokkosdevice(LAMMPS* lmp) {
+  return new PairDPA4SpinKokkos<LMPDeviceType>(lmp);
+}
+static Pair* pairdpa4spinkokkoshost(LAMMPS* lmp) {
+  return new PairDPA4SpinKokkos<LMPHostType>(lmp);
+}
+#endif
+
 static Compute* computedeepmdtensoratom(LAMMPS* lmp, int narg, char** arg) {
   return new ComputeDeeptensorAtom(lmp, narg, arg);
 }
@@ -48,6 +69,37 @@ extern "C" void lammpsplugin_init(void* lmp, void* handle, void* regfunc) {
   plugin.handle = handle;
   (*register_plugin)(&plugin, lmp);
 
+#ifdef LMP_KOKKOS
+  plugin.version = LAMMPS_VERSION;
+  plugin.style = "pair";
+  plugin.name = "deepmd/kk";
+  plugin.info = "deepmd Kokkos pair style " STR_GIT_SUMM;
+  plugin.author = "Tiancheng Li";
+  plugin.creator.v1 = (lammpsplugin_factory1*)&pairdeepmdkokkosdevice;
+  plugin.handle = handle;
+  (*register_plugin)(&plugin, lmp);
+
+  plugin.name = "deepmd/kk/device";
+  (*register_plugin)(&plugin, lmp);
+
+  plugin.name = "deepmd/kk/host";
+  plugin.creator.v1 = (lammpsplugin_factory1*)&pairdeepmdkokkoshost;
+  (*register_plugin)(&plugin, lmp);
+
+  plugin.name = "dpa4spin/kk";
+  plugin.info = "dpa4spin Kokkos pair style " STR_GIT_SUMM;
+  plugin.author = "Tiancheng Li";
+  plugin.creator.v1 = (lammpsplugin_factory1*)&pairdpa4spinkokkosdevice;
+  (*register_plugin)(&plugin, lmp);
+
+  plugin.name = "dpa4spin/kk/device";
+  (*register_plugin)(&plugin, lmp);
+
+  plugin.name = "dpa4spin/kk/host";
+  plugin.creator.v1 = (lammpsplugin_factory1*)&pairdpa4spinkokkoshost;
+  (*register_plugin)(&plugin, lmp);
+#endif
+
   plugin.version = LAMMPS_VERSION;
   plugin.style = "pair";
   plugin.name = "deepspin";