Fix Linux ARM64 legacy CMake resolution

[tctco]

Summary

• pin the manylinux2014 container CMake to 3.31.10
• replace transitive Conan cmake/* tool requirements with that platform-provided executable
• make the legacy build script apply the dedicated Conan profile in both host and build contexts

Root cause

The v4.2.4 ARM64 release job downloaded Conan CMake 3.31.12 and 4.4.0 ARM64 binaries. Those executables require GLIBC 2.25/2.28 and cannot run in the manylinux2014 GLIBC 2.17 container, causing the expat build to fail.

Validation

• bash -n scripts/docker-build-core.sh
• git diff --check
• manylinux2014 container reports CMake 3.31.10
• fresh Conan dependency graph resolves all five transitive CMake ranges to cmake/3.31.10#platform and downloads no Conan CMake binary

Failed release run: https://github.com/tctco/DCCCSlicer/actions/runs/29936695109

[tctco]

The first v4.2.4 release run exposed one additional Windows-only test failure after the ARM64 failure was fixed. Path(...).expanduser() rewrote the synthetic POSIX path in the macOS Gatekeeper hint test to Windows separators. Commit 0439d0c now uses os.path.expanduser(os.fspath(...)), preserving the caller's path text. Validation: the focused UI test file passes all 4 tests, and ntpath.expanduser('/tmp/plugin/cpp/CentiloidCalculator') preserves the expected path. The failed release run otherwise reported 107 passed and 6 skipped on Windows.