Emit N documents (one per node; no replica field) using the real
arbitrage.oleks.space/v1alpha1 schema: top-level class + requirements
{arch,cores,ramGb}, namespace builder-arbitrage, class label. Rename
public API to render_ephemeral_builders; wire --node-ram-gb into ramGb.
_recommend assumes sorted, deduped grids (core_grid[-1] = biggest, knee
sweeps run low->high). The CLI parsed --nodes/--cores in raw order, so
e.g. --cores 32,8,16 yielded nonsense. Sort+dedupe in cli.py and reject
non-positive/non-integer values; also normalize defensively inside
estimate() so the function is correct for any caller. Add estimate/cli
tests.
Oleks