fix(ci): add imagePullPolicy: IfNotPresent to training workflow

Kubernetes defaults to Always for :latest tags, forcing registry
round-trips that fail on fresh GPU nodes where containerd HTTP-only
registry config has a race condition with HTTPS fallback.

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

infra/k8s/argo/training-workflow-template.yaml

@@ -26,7 +26,7 @@ spec:
     parameters:
       - name: model
       - name: gpu-pool
-        value: ci-training-h100
+        value: ci-training-h100  # Pools: ci-training-h100, ci-training-l40s, ci-training-h100x2
       - name: hyperopt-trials
         value: "20"
       - name: hyperopt-epochs
@@ -97,6 +97,7 @@ spec:
           effect: NoSchedule
       container:
         image: gitlab-registry.foxhunt.svc.cluster.local:5000/root/foxhunt/foxhunt-training-runtime:latest
+        imagePullPolicy: IfNotPresent
         command: ["/bin/sh", "-c"]
         args:
           - |
@@ -118,6 +119,7 @@ spec:
         k8s.scaleway.com/pool-name: platform
       container:
         image: gitlab-registry.foxhunt.svc.cluster.local:5000/root/foxhunt/foxhunt-runtime:latest
+        imagePullPolicy: IfNotPresent
         command: ["/bin/sh", "-c"]
         args:
           - |
@@ -168,6 +170,7 @@ spec:
           effect: NoSchedule
       container:
         image: gitlab-registry.foxhunt.svc.cluster.local:5000/root/foxhunt/foxhunt-training-runtime:latest
+        imagePullPolicy: IfNotPresent
         command: ["/bin/sh", "-c"]
         args:
           - |
@@ -264,6 +267,7 @@ spec:
           effect: NoSchedule
       container:
         image: gitlab-registry.foxhunt.svc.cluster.local:5000/root/foxhunt/foxhunt-training-runtime:latest
+        imagePullPolicy: IfNotPresent
         command: ["/bin/sh", "-c"]
         args:
           - |
@@ -355,6 +359,7 @@ spec:
           effect: NoSchedule
       container:
         image: gitlab-registry.foxhunt.svc.cluster.local:5000/root/foxhunt/foxhunt-training-runtime:latest
+        imagePullPolicy: IfNotPresent
         command: ["/bin/sh", "-c"]
         args:
           - |
@@ -429,6 +434,7 @@ spec:
         k8s.scaleway.com/pool-name: platform
       container:
         image: gitlab-registry.foxhunt.svc.cluster.local:5000/root/foxhunt/foxhunt-runtime:latest
+        imagePullPolicy: IfNotPresent
         command: ["/bin/sh", "-c"]
         args:
           - |