fix(train): correct --output to --output-dir arg, add Prometheus annotations

The train_baseline_rl binary expects --output-dir, not --output.
Also adds prometheus.io scrape annotations to job pod templates
so training metrics appear in Grafana.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

infra/scripts/train.sh

@@ -157,7 +157,7 @@ generate_job_manifest() {
   local cli_args=("--model" "$model" "--symbol" "$SYMBOL" "--data-dir" "/data/futures-baseline")
   cli_args+=("--mbp10-data-dir" "/data/futures-baseline-mbp10")
   cli_args+=("--trades-data-dir" "/data/futures-baseline-trades")
-  cli_args+=("--output" "/output")
+  cli_args+=("--output-dir" "/output")
   if [[ "$PRESET" == "hyperopt" ]]; then
     cli_args+=("--trials" "$TRIALS")
   fi
@@ -186,6 +186,10 @@ spec:
   ttlSecondsAfterFinished: 600
   template:
     metadata:
+      annotations:
+        prometheus.io/scrape: "true"
+        prometheus.io/port: "9094"
+        prometheus.io/path: "/metrics"
       labels:
         app.kubernetes.io/part-of: foxhunt
         app.kubernetes.io/component: training-workflow