Add initialization checking in BFGS, and replace the old BFGS with a new one in CG-BFGS.

[19hello]

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[Copilot]

Pull request overview

This PR updates the ionic relaxation flow to switch cg_bfgs into the newer/traditional BFGS implementation safely (by adding lazy initialization), and also modifies the OpenMPI stage1 build configuration.

Changes:

• Switch cg_bfgs -> bfgs handoff to select relax_method[1] = "1" (the BFGS/bfgs_trad path).
• Add lazy initialization (is_initialized) to BFGS so relax_step() can be called safely without a prior explicit allocate().
• Update the OpenMPI installer to pass explicit compiler selections to ./configure.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
toolchain/scripts/stage1/install_openmpi.sh	Forces compiler variables during OpenMPI configure (may affect toolchain portability).
source/source_relax/ions_move_cg.cpp	Changes the cg_bfgs threshold switch to select bfgs_trad (relax_method[1]="1").
source/source_relax/bfgs.h	Adds an is_initialized flag to support safe lazy initialization.
source/source_relax/bfgs.cpp	Lazily calls allocate() from relax_step() if needed.

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[Copilot]

Hardcoding CC=gcc, CXX=g++, FC=gfortran, and F77=gfortran here overrides any compiler selection coming from toolchain.conf/toolchain.env (e.g., Intel/Clang toolchains, cross-compilers) and can make OpenMPI fail to build on systems without GNU Fortran installed. Consider respecting existing environment/toolchain variables (e.g., CC="${CC:-gcc}" etc.) or omitting these assignments and letting the toolchain drive the compiler choice, consistent with the other MPI install scripts.

Suggested change

	CC=gcc \
	CXX=g++ \
	FC=gfortran \
	F77=gfortran \
	CC="${CC:-gcc}" \
	CXX="${CXX:-g++}" \
	FC="${FC:-gfortran}" \
	F77="${F77:-gfortran}" \

[Copilot]

relax_step() now lazily calls allocate() when the object hasn't been initialized. There are existing unit tests for BFGS in source/source_relax/test/bfgs_test.cpp, but none cover this new path (calling relax_step() without a prior allocate()). Please add a test to assert that relax_step() succeeds and initializes internal state when allocate() was not called explicitly (this is particularly important for the cg_bfgs -> bfgs_trad switch).