[ci skip] Add tier labels to all namespace resources for Kyverno resource governance

Added `tier = var.tier` to kubernetes_namespace labels in ~73 service
modules. This enables Kyverno to generate LimitRange defaults,
ResourceQuotas, and PriorityClass injection for all namespaces.

Previously only 11 namespaces had tier labels; now all 80 active
namespaces are labeled. All pods restarted in rolling waves to pick
up the new policies.

modules/kubernetes/hackmd/main.tf

@@ -7,6 +7,7 @@ resource "kubernetes_namespace" "hackmd" {
     name = "hackmd"
     labels = {
       "istio-injection" : "disabled"
+      tier = var.tier
     }
   }
 }