chore: remove per-step determinism diagnostic

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/ml/src/trainers/dqn/fused_training.rs

@@ -1042,12 +1042,6 @@ impl FusedTrainingCtx {
             PhaseEvents::record(pe.adam_end, cu_stream);
         }
 
-        // ── DETERMINISM DIAG ──
-        if step < 40 {
-            let mut dl = [0.0_f32];
-            self.stream.memcpy_dtoh(&self.trainer.total_loss_buf, &mut dl).ok();
-            tracing::warn!("STEP_DIAG step={step} loss={:.10}", dl[0]);
-        }
         // ── Step 6: PER priority update ─────────────────────────────────
         if let Some(ref pe) = self.phase_events {
             PhaseEvents::record(pe.per_update_start, cu_stream);