Refactor: remove some unhealthy include dependencies (#7512)

* refactor(pw): remove dead esolver include from hamilt_pw.h

HamiltPW does not reference any ESolver symbol; the include of
source_esolver/esolver_ks_pw.h was unused. Removing it cuts the only
source_pw -> source_esolver back-edge (an operator header depending on
its driver) and drops 15 transitively-included headers from every
consumer of hamilt_pw.h (fan 114 -> 99).

All types named in the header (UnitCell, ModulePW::PW_Basis_K, etc.)
remain provided by klist.h / vnl_pw.h -> structure_factor.h.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* refactor(surchem): forward-declare pw types in surchem.h

Structure_Factor and Parallel_Grid are used in surchem.h only as
pointer/reference parameters, so replace the heavy source_pw includes
with forward declarations. This cuts the hamilt -> pw back-edge from
surchem.h (hamilt->pw edge 4 -> 2) and drops 6 transitively-included
headers from surchem.h's closure (54 -> 48), benefiting its ~160
transitive consumers.

Two consumers relied on the transitive include and now include it
directly (include-what-you-use):
- esolver_fp.h: has a Parallel_Grid value member -> add parallel_grid.h
- forces.cpp: accesses p_sf->strucFac -> add structure_factor.h

Other surchem.h consumers use these types only via pointer/reference
and are covered by the forward declarations; verified the remaining
parallel_grid.h users still reach it through other includes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* fix(surchem): include structure_factor.h in cal_pseudo.cpp

cal_pseudo.cpp dereferences Structure_Factor (sf->strucFac) but only
included surchem.h, which now forward-declares the type. Add the direct
include so the complete type is available. Fixes the CI build error
"invalid use of incomplete type 'class Structure_Factor'".

Verified via closure analysis that this is the only remaining file in
surchem.h's affected set that requires the complete type; all other
consumers use Structure_Factor / Parallel_Grid by pointer or reference.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* style(surchem): drop verbose comment on forward declarations

Match the house style used across the codebase (e.g. makov_payne.h,
exx_helper_base.h, cube_io.h), where forward declarations are bare
`class Foo;` lines without an explanatory comment.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* style(surchem): add a one-line note on the forward declarations

Brief comment explaining why the source_pw types are forward-declared
(pointer/reference use only) so the includes are not re-added later.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: Critsium-xy

source/source_esolver/esolver_fp.h

@@ -9,6 +9,7 @@
 #include "source_estate/elecstate.h" // electronic states
 #include "source_estate/module_charge/charge_extra.h" // charge extrapolation
 #include "source_hamilt/module_surchem/surchem.h" // solvation model
+#include "source_pw/module_pwdft/parallel_grid.h" // Parallel_Grid (value member below)
 #include "source_pw/module_pwdft/vl_pw.h" // local pseudopotential
 #include "source_pw/module_pwdft/structure_factor.h" // structure factor
 

source/source_hamilt/module_surchem/cal_pseudo.cpp

@@ -1,5 +1,7 @@
 #include "surchem.h"
 
+#include "source_pw/module_pwdft/structure_factor.h" // Structure_Factor member access (sf->strucFac)
+
 // atom_in surchem::GetAtom;
 
 void surchem::gauss_charge(const UnitCell& cell,

source/source_hamilt/module_surchem/surchem.h

@@ -6,8 +6,10 @@
 #include "source_base/matrix.h"
 #include "source_basis/module_pw/pw_basis.h"
 #include "source_cell/unitcell.h"
-#include "source_pw/module_pwdft/parallel_grid.h"
-#include "source_pw/module_pwdft/structure_factor.h"
+
+// forward-declared: used below only as pointer/reference
+class Parallel_Grid;
+class Structure_Factor;
 
 class surchem
 {

source/source_pw/module_pwdft/forces.cpp

@@ -17,6 +17,7 @@
 #include "source_estate/module_pot/gatefield.h"
 #include "source_hamilt/module_ewald/H_Ewald_pw.h"
 #include "source_hamilt/module_surchem/surchem.h"
+#include "source_pw/module_pwdft/structure_factor.h" // Structure_Factor member access (p_sf->strucFac)
 #include "source_hamilt/module_vdw/vdw.h"
 
 #ifdef _OPENMP

source/source_pw/module_pwdft/hamilt_pw.h

@@ -4,7 +4,6 @@
 #include "source_base/kernels/math_kernel_op.h"
 #include "source_base/macros.h"
 #include "source_cell/klist.h"
-#include "source_esolver/esolver_ks_pw.h"
 #include "source_estate/module_pot/potential_new.h"
 #include "source_hamilt/hamilt.h"
 #include "source_lcao/module_dftu/dftu.h" // mohan add 2025-11-06