feat(supervisor): add Kubernetes worker pod priority class support

Add KUBERNETES_POD_PRIORITY_CLASS_NAME environment variable to allow
configuring a priority class for task run pods in Kubernetes environments.

This addresses pod preemption issues in resource-constrained clusters,
particularly in GKE Autopilot where low-priority pods can be preempted
by system pods during scale-up operations.

Fixes: Pod preemption causing SIGTERM failures during cluster scale-up
Related: GKE Autopilot resource contention

Author: NERLOE

apps/supervisor/src/env.ts

@@ -111,6 +111,7 @@ const Env = z.object({
   KUBERNETES_MEMORY_OVERHEAD_GB: z.coerce.number().min(0).optional(), // Optional memory overhead to add to the limit in GB
   KUBERNETES_SCHEDULER_NAME: z.string().optional(), // Custom scheduler name for pods
   KUBERNETES_LARGE_MACHINE_POOL_LABEL: z.string().optional(), // if set, large-* presets affinity for machinepool=<value>
+  KUBERNETES_POD_PRIORITY_CLASS_NAME: z.string().optional(), // Priority class name for task run pods
 
   // Placement tags settings
   PLACEMENT_TAGS_ENABLED: BoolEnv.default(false),

apps/supervisor/src/workloadManager/kubernetes.ts

@@ -320,6 +320,11 @@ export class KubernetesWorkloadManager implements WorkloadManager {
             },
           }
         : {}),
+      ...(env.KUBERNETES_POD_PRIORITY_CLASS_NAME
+        ? {
+            priorityClassName: env.KUBERNETES_POD_PRIORITY_CLASS_NAME,
+          }
+        : {}),
     };
   }