fix immich TF drift from Kyverno ndots injection, right-size nvidia GPU operator

- immich: add lifecycle ignore_changes for dns_config on all 3 deployments
  to prevent perpetual plan drift from Kyverno ndots:2 mutation policy
- nvidia dcgm-exporter: 768Mi → 2560Mi (VPA upper 2091Mi, was under-provisioned)
- nvidia cuda-validator: 1024Mi → 256Mi (one-shot job, vastly over-provisioned)

stacks/platform/modules/nvidia/values.yaml

@@ -18,6 +18,22 @@ driver:
     config:
       name: time-slicing-config
 
+# DCGM Exporter - increased from 768Mi to 2560Mi based on VPA upper bound of 2091Mi
+dcgmExporter:
+  resources:
+    requests:
+      memory: "2560Mi"
+    limits:
+      memory: "2560Mi"
+
+# CUDA Validator - reduced from 1024Mi to 256Mi (one-shot job)
+validator:
+  resources:
+    requests:
+      memory: "256Mi"
+    limits:
+      memory: "256Mi"
+
 # Tolerate GPU node taint for all GPU operator components
 daemonsets:
   tolerations: