source_cell / source_pw: remove four more #define private public

[Critsium-xy]

source_cell / source_pw: remove four more #define private public

Continues the cleanup (#7940, #7949, #7952, #7953). Four macros come off, and
in three of the four files nothing is granted to anyone.

• read_sep_test.cpp is vestigial: it carries the macro but touches nothing
  private in sep.h. The directives are deleted and nothing else changes, as
  with cal_test.cpp and test_hsolver.cpp in source_relax: pass INPUT values explicitly instead of reading PARAM, removing the test access hacks it caused #7921.

• soc_test.cpp read soc.p_rot[l2p1*i + n] five times, while Soc has a
  public rotylm(i1, i2) returning exactly p_rot[l2plus1_*i1 + i2]. Those
  become soc.rotylm(i, n) / soc.rotylm(i+1, n).

  The sixth use was EXPECT_NE(soc.p_rot, nullptr). That assertion is dropped
  rather than kept alive with a friend declaration: the next line already calls
  soc.rotylm(0, 0) and checks its value, which covers both "was it allocated"
  and "is it correct", and the guard was EXPECT_ rather than ASSERT_, so it
  did not even stop the dereference that follows. soc.h is therefore
  untouched by this PR.

• atom_spec_test.cpp calls the private Pseudopot_upf::read_pseudo_upf201,
  which writes thirteen members of its object and has no stateless form. It
  gets friend class AtomSpecTest; alongside the AtomPseudoTest, NCPPTest
  and ReadPPTest grants already there from source_cell: replace #define private public with named friend grants in four tests #7949, plus a forwarding wrapper.
  The atom.type and atom.ncpp accesses in the same file are public members
  of Atom and never needed the macro.

• sltk_grid_test.cpp wrote PARAM.input.test_grid = 1 only to pass it into
  Grid LatGrid(PARAM.input.test_grid) -- PARAM used as a local, so it becomes
  one. Its genuine private access is Grid::setMemberVariables, 117 lines
  setting members from a UnitCell, so that gets friend class SltkGridTest;
  and a wrapper. Grid::pbc and Grid::sradius2, also read here, are public.

Friendship is not inherited and a TEST_F body lives in a derived class, hence
the wrappers -- the arrangement established in #7949.

An earlier revision also removed the macro from memory_test.cpp and the three
propagator_test*.cpp. Compiling without it showed both readings wrong:
memory_test reads Memory::name, class_name, consume and init_flag,
private statics reached through :: rather than a member access; the propagator
tests read PARAM.input, so they are reason-(a) work. Both are left alone, per
the rule this series follows: remove the macro, or leave the file untouched.

Macro occurrences 88 -> 84. Production change is two friend declarations, one
of them added to a list that already exists.

Co-Authored-By: Claude Opus 5 (1M context) noreply@anthropic.com

Verification

Linux, cmake -B build -G Ninja -DBUILD_TESTING=ON -DENABLE_LCAO=ON -DENABLE_MPI=ON -DENABLE_OPENMP=ON:

• Build: the only failing target is source_lcao/module_lr/.../lr_io_krlist.cpp.o,
  on ri_util.h: RI/global/Array_Operator.h: No such file or directory. That is
  pre-existing on develop in an environment without LibRI headers (from Refactor LR_IO function and add test case 58_KP_LR_BSE #7849);
  this PR touches neither file.
• All five affected tests pass: MODULE_CELL_NEIGHBOR_sltk_grid,
  MODULE_CELL_atom_spec, MODULE_CELL_read_sep_parallel,
  MODULE_CELL_sep_cell_parallel, MODULE_PW_pwdft_soc.
• agent_governance_check.py --base upstream/develop --head HEAD: 0 errors. The
  access-hack ratchet reports nothing (4 removed, 0 added), and no
  PARAM/GlobalV/GlobalC reference is added or removed.

No INPUT parameter and no user-visible behaviour changed, so
docs/parameters.yaml and docs/advanced/input_files/input-main.md need no update.

🤖 Generated with Claude Code