host_memory_available() raises ValueError on macOS #70

Bug description

The host_memory_available() function falls back to os.sysconf("SC_AVPHYS_PAGES") when /proc/meminfo is unavailable.

On macOS, this raises ValueError: unrecognized configuration name, preventing the CPU MPO–MPO benchmark from completing.

Steps to reproduce

On macOS, run the CPU MPO–MPO benchmark from the repository root: python benches/primitives/bench_mpo_mpo.py --n-sites 4 --chi-out 8 --chi-id 4 --run src --compare no --device cpu

Expected behavior

The function should return the available host memory on macOS without raising an exception, allowing the CPU benchmark to complete successfully.

Device

CPU (NumPy)

Versions

Python: 3.12.9
NumPy: 2.3.5
src-method: 0.1.dev51+gbd78e23b3

Operating system

macOS (Intel)

Additional context

No response