Feature: velocity matrix correction for meta-gga xc functionals

[Flying-dragon-boxing]

See the title for details.

[Copilot]

Pull request overview

This PR extends the PW velocity operator used by conductivity calculations to include a meta-GGA (v_\tau)-dependent commutator contribution, enabling a corrected “velocity matrix” when meta-GGA XC functionals are selected.

Changes:

• Thread meta-GGA (v_\tau) (from Potential::vofk_smooth) into hamilt::Velocity from PW and SDFT conductivity drivers.
• Implement a meta-GGA velocity correction term in Velocity::act() using real/reciprocal transforms and meta_pw_op.
• Refactor EXX inner-loop set_psi() placement in ESolver_KS_PW::iter_finish() to avoid redundant calls.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
source/source_pw/module_stodft/sto_elecond.cpp	Passes vofk_smooth data (as (v_\tau)) into Velocity for STO conductivity.
source/source_pw/module_pwdft/op_pw_vel.h	Extends Velocity API/state to accept/store (v_\tau) and work buffers.
source/source_pw/module_pwdft/op_pw_vel.cpp	Implements meta-GGA commutator-based velocity correction and allocates new workspaces.
source/source_pw/module_pwdft/elecond.cpp	Passes vofk_smooth data (as (v_\tau)) into Velocity for KG conductivity.
source/source_esolver/esolver_ks_pw.cpp	Adjusts EXX set_psi() call timing in the separate-loop path.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Qianruipku]

Please make some changes according to Copilot’s suggestions.