fix: pass MDCell ghost communication plan to DeePMD

[19hello]

Reminder

• I have read AGENTS.md and docs/developers_guide/agent_governance.md.
• I have linked an issue or explained why this PR does not need one.
• I have added adequate unit tests and case tests.
• I have listed the exact verification commands and results.
• I have described user-visible behavior changes, including INPUT parameter changes.
• I have explained core-module impact.
• No governance exception is requested.

Linked Issue

Fix #8108

Unit Tests and/or Case Tests for my changes

Configuration and build

cmake -S . -B /tmp/abacus-issue8108-deepmd-c-build2 \
  -DENABLE_MPI=ON \
  -DENABLE_LCAO=OFF \
  -DBUILD_TESTING=ON \
  -DDeePMD_DIR=/home/fy19/00_software/deepmd-kit-c \
  -DCMAKE_EXE_LINKER_FLAGS=-Wl,--allow-shlib-undefined

Result:

DeePMD_HAS_COMM_NLIST - Success

cmake --build /tmp/abacus-issue8108-deepmd-c-build2 \
  --target abacus_pw_para -j4

Result:

Built target abacus_pw_para

#### Domain decomposition tests

env LD_PRELOAD=/usr/lib/x86_64-linux-gnu/openblas-pthread/libopenblas.so.0 \
  /home/fy19/abacus-develop/toolchain/install/openmpi-5.0.10/bin/mpiexec \
  -n 4 \
  /tmp/abacus-issue8108-deepmd-c-build2/source/source_cell/module_neighlist/test/MODULE_CELL_NEIGHBOR_mdcell_migrate_mpi \
  --gtest_filter=DomainDecompositionTest.*

Result:

12 tests passed on 4 MPI ranks.

The focused GhostExchangePlanMatchesGhostLayout test also passed on 1 and 4 MPI ranks.

#### DeePMD MD case

Case:

md_test/test_for_XZC

Model:

B_graph_compress_new_op.pth

1-rank command:

env OMP_NUM_THREADS=1 \
  LD_PRELOAD=/usr/lib/x86_64-linux-gnu/openblas-pthread/libopenblas.so.0 \
  LD_LIBRARY_PATH=/home/fy19/00_software/deepmd-kit-c/lib:$LD_LIBRARY_PATH \
  /home/fy19/abacus-develop/toolchain/install/openmpi-5.0.10/bin/mpiexec \
  -n 1 \
  /tmp/abacus-issue8108-deepmd-c-build2/abacus_pw_para

4-rank command:

env OMP_NUM_THREADS=1 \
  LD_PRELOAD=/usr/lib/x86_64-linux-gnu/openblas-pthread/libopenblas.so.0 \
  LD_LIBRARY_PATH=/home/fy19/00_software/deepmd-kit-c/lib:$LD_LIBRARY_PATH \
  /home/fy19/abacus-develop/toolchain/install/openmpi-5.0.10/bin/mpiexec \
  -n 4 \
  /tmp/abacus-issue8108-deepmd-c-build2/abacus_pw_para

Result:

Both 1-rank and 4-rank MD cases completed 5 MD steps successfully.
The first-step energies agreed between 1-rank and 4-rank runs.
No ghost mapping or MPI communication error occurred.

Additional checks:

git diff --check

Result:

Passed

python3 tools/03_code_analysis/agent_governance_check.py --staged

Result:

No blocking findings.

#### Checks not run

- No explicit DPA-2/repformers model was available in the test case, so a model-specific regression was not run.
- The complete repository test suite was not run; focused module tests and the relevant DeePMD MD case were run instead.
- CI checks remain to be executed by the pull request workflow.

The MPI runs used OMP_NUM_THREADS=1 and an OpenBLAS preload to work around the host BLAS alternatives environment, which otherwise caused a gotoblas lookup failure.

### What's changed?

- Add GhostExchangePlan to describe the ghost communication metadata required by DeePMD.
- Make DomainDecomposition build the plan from its internal ghost exchange slots.
- Store the current plan in MDCell.
- Pass the communication metadata from MDCell to ESolver_DP.
- Construct the 13-argument communication-capable DeePMD InputNlist when supported.
- Preserve the original 4-argument InputNlist fallback for older DeePMD-kit APIs.
- Use mapping only for the single-rank path where periodic ghost atoms are folded onto local real atoms.
- Use the communication plan without local mapping for multi-rank runs.
- Reduce DeePMD API preprocessor duplication with the DPInputNlist type alias.
- Rename the interfaces to build_ghost_exchange_plan() and get_ghost_exchange_plan().
- Add unit coverage for the generated ghost exchange plan.

### Governance Notes

- INPUT/docs changes: None. No INPUT parameters or user-facing INPUT behavior were changed.
- Core module impact: This change affects ESolver_DP, MDCell, and DomainDecomposition. It does not modify HSolver, ElecState, Hamilt, Operator, or Psi.
- Header dependencies: GhostExchangePlan is kept in a small dedicated header so MDCell and DomainDecomposition can share the communication data type without including each other’s full headers.
- Exceptions requested: None.

[ABACUS-PR-BOT]

Static review of ffd66c4: three API/build compatibility issues and two nonblocking follow-ups below. No builds or model runs were performed; CI diagnostics were unavailable through the selected-account connector.