REFACTOR(traefik): change traefik anti-affinity

- from hard to soft
- Use preferredDuringSchedulingIgnoredDuringExecution instead of
  required
- Allows pods to be scheduled on same node if necessary
- Still prefers distribution across nodes (weight: 100)

traefik/helm-values.yaml

@@ -9,11 +9,13 @@ spec:
     deployment:
       replicas: 3
 
-    # Pod Anti-Affinity - 각 노드에 최대 1개씩만 배치
+    # Pod Anti-Affinity - 가능하면 각 노드에 분산 배치 (soft)
     affinity:
       podAntiAffinity:
-        requiredDuringSchedulingIgnoredDuringExecution:
-          - labelSelector:
+        preferredDuringSchedulingIgnoredDuringExecution:
+          - weight: 100
+            podAffinityTerm:
+              labelSelector:
                 matchLabels:
                   app.kubernetes.io/name: traefik
               topologyKey: kubernetes.io/hostname