5f49a5adca
env_for() mapped --gpu/--vram only inside the --auto-tier branch, so the standalone form started a CPU-only engine with no warning (#121 — nearly published as a GPU benchmark). Now: --gpu none disables CUDA; --gpu list/auto sets COLI_CUDA/COLI_GPUS; --vram sets CUDA_EXPERT_GB; and --gpu/--vram on a CPU-only binary exit with a clear 'make glm CUDA=1' message instead of falling back silently. Tested on a CPU-only build: fail-fast fires for --gpu/--vram, --gpu none and default still start the CPU engine (no regression).