feat(dqn-v2): C.6 Task 14 — epsilon GPU kernel + CPU monitor (exploration)
epsilon_update kernel computes effective epsilon from ISV[EPOCH_IDX=39,
TOTAL_EPOCHS=40, LEARNING_HEALTH=12] with cosine schedule (eps_start ->
eps_end) plus health-coupled boost (up to +0.1 at collapse). Single-thread
cold-path kernel writes ISV[EPSILON_EFF_INDEX=41].
EpsilonMonitor is a read-only observer exposing eps_eff, epoch_idx,
total_ep, health, progress, fire_rate in DiagSnapshot.
Wires epsilon kernel launch at epoch boundary alongside tau kernel. Consumer
migration: log_training_config ISV-adaptive epsilon block now reads
ISV[EPSILON_EFF_INDEX] instead of computing `base_floor * (0.5 + volatility)`.
Tests: 3 monitor unit tests pass. cargo check -p ml at 8-warning baseline.
Plan 1 Task 14. Spec §4.C.6 (2026-04-24 revision).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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