Fix local pseudopotential energy calculation with k-point parallelization

[A-006]

Description

Fixes an overcounting bug in the local pseudopotential energy (E_local_pp) when using k-point parallelization (kpar > 1).

Problem

When kpar > 1, the real-space charge density and local pseudopotential are:

• Distributed within each k-point pool (i.e., across processes in the same pool),
• But duplicated across different k-point pools.

The previous implementation used Parallel_Reduce::reduce_all to sum E_local_pp, which aggregates values from all MPI processes across all pools. This caused the local pseudopotential energy to be overcounted by a factor of kpar, leading to incorrect total energies in both KS-DFT and OF-DFT calculations.

Solution

Replaced Parallel_Reduce::reduce_all with Parallel_Reduce::reduce_pool in:

• source/elecstate/elecstate_energy_terms.cpp (KS-DFT)
• source/esolver/esolver_of.cpp (OF-DFT)

reduce_pool performs reduction only within the current k-point pool communicator—where the real-space grid data is uniquely partitioned—ensuring the energy is summed exactly once.