Extends MultiHorizonLoaderConfig with `outcome_label_cost` (default
DEFAULT_OUTCOME_LABEL_COST_ES = 0.5 = 2 ticks for ES round-trip).
LabeledSequence + LoadedFile gain outcome_long + outcome_short arrays
of [Vec<f32>; N_HORIZONS] populated by generate_outcome_labels_d during
LoadedFile construction (same !inference_only branch as BCE labels).
CLI exposure: alpha_train.rs gains --outcome-label-cost flag with the
ES default. All 6 MultiHorizonLoaderConfig consumers updated atomically
per feedback_no_partial_refactor: alpha_train (train + val loaders),
in-file test fixtures (×2), multi_horizon_loader.rs (×2), harness.rs,
trainer_parity.rs, ring3_replay.rs.
cargo check --workspace clean; ml-alpha lib tests 41 passed.
B3+ tasks not yet touched: outcome labels are computed and propagated to
LabeledSequence but no consumer reads them yet (aux trunk Tasks B3-B5
will wire that).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
859d0c738b