[codex] Wrap libneo hdf5_tools in KAMEL

[krystophny]

Summary

• replace the vendored common/hdf5_tools implementation with a thin compatibility layer over canonical LIBNEO::hdf5_tools
• keep KAMEL_hdf5_tools as the local module surface so KIM and QL-Balance do not need a broad call-site rewrite
• make every KAMEL subproject share one libneo build tree and module include directory

Why

KAMEL was carrying its own divergent hdf5_tools implementation.

This PR keeps the KAMEL-facing module name stable, but moves the real implementation back to canonical libneo code. The compatibility layer only preserves the legacy specific entry points that QL-Balance still links against directly.

Linked work

• libneo issue: Dependency audit: downstream map, duplication report, and split proposals libneo#258
• sparse_draft sibling PR: https://github.com/itpplasma/sparse_draft/pull/15
• benchmark_orbit sibling PR: [codex] Discover current SIMPLE libneo build outputs benchmark_orbit#1

Verification

cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DINSTALL_KIM_SYMLINK=OFF -DPython_EXECUTABLE=/usr/bin/python3
cmake --build build -j$(nproc)
ctest --test-dir build --output-on-failure

Result: KIM.x, ql-balance.x, and fouriermodes.x build successfully, and ctest passes 18/18 after the full build.