refactor(cell): replace raw pointer members with std::vector in Symmetry

[DanielZhao0432]

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/or case tests, or explained why not.
• I have listed the exact verification commands run and their results.
• I have described user-visible behavior changes, including INPUT parameter changes.
• I have explained core-module impact for ESolver, HSolver, ElecState, Hamilt, Operator, Psi, or other source/ changes.
• I have requested any needed governance exception below.

Linked Issue

No linked issue: this is a small internal refactor with no behavior change.

Unit Tests and/or Case Tests for my changes

• Commands run:
  • cmake --build build -j30 (full build with BUILD_TESTING=ON, ENABLE_MPI=ON)
  • OMP_NUM_THREADS=1 ctest --test-dir build -R MODULE_CELL_SYMMETRY (covers analy_sys/pricell/getgroup and density symmetrization)
  • OMP_NUM_THREADS=1 ctest --test-dir build -R "MODULE_CELL_(klist|qlist|little_group)" (regression: these tests call analy_sys indirectly)
  • python3 tools/03_code_analysis/agent_governance_check.py --staged
• Result summary: build succeeded; MODULE_CELL_SYMMETRY 4/4 passed; klist/qlist/little_group 5/5 passed; governance check reported only non-blocking warnings (addressed in Governance Notes).
• Checks not run, with reason: no new tests added — no behavior change; the existing symmetry unit tests already exercise the modified lifecycle (analy_sys allocates/fills/releases these arrays every call).

What's changed?

• Replaced the five raw-pointer members of ModuleSymmetry::Symmetry with std::vector: int* na, int* istart -> std::vector<int>; double* newpos, double* rotpos -> std::vector<double>; int* index -> std::vector<int>.
• In analy_sys (symm_analysis.cpp): merged the new[] + ModuleBase::GlobalFunc::ZEROS pairs into assign(n, 0) calls (keeping the exact sizes, including nat + 2 for index), which also re-zeroes correctly when analy_sys is called repeatedly (e.g. each ionic step of cell-relax); removed the five delete[] at the end of the function.
• Member-to-function call sites now pass .data(): lattice_type, pricell, getgroup in symm_analysis.cpp; getgroup in symm_magnetic.cpp; two pointer-arithmetic call sites of atom_ordering_new in symm_pricell.cpp (index.data() + istart[it], rotpos.data() + istart[it] * 3).
• In set_atom_map (symmetry.cpp): replaced ZEROS(pos, nat*3) with std::fill(this->newpos.begin(), this->newpos.end(), 0.0) per the AGENTS.md rule on vector buffers, and the local aliases use .data().
• Function signatures of getgroup/checksym/pricell/lattice_type are unchanged: they still take raw pointers because irred_sec_bvk.cpp and symm_magnetic.cpp pass non-member local buffers, and lattice_type's newpos argument is nullptr in 4 of its 5 call sites.

Governance Notes

• INPUT/docs changes: none; no INPUT parameter or user-visible behavior changed, so docs/parameters.yaml and docs/advanced/input_files/input-main.md do not require updates.
• Core module impact: confined to source_cell/module_symmetry; a tree-wide search confirms no code outside the module accesses these five members, and no test or mock defines the Symmetry constructor/destructor.
• The GlobalV warning on symm_magnetic.cpp:73 is migration-neutral (net_delta=0): the edited getgroup call line merely re-wraps the existing GlobalV::ofs_running reference.
• The header-include warning on symmetry.h (#include <vector>) is acceptable: the class holds std::vector value members, which require the complete type.
• Exceptions requested: none.