## Summary
- New `apps/base/priority-classes/` app with four `PriorityClass` objects managed via the `platform` ArgoCD project
- Adds `apps/overlays/*/priority-classes` to the platform ApplicationSet generator
- Adds `priority-classes` namespace to platform AppProject destinations (required even for cluster-scoped resources)
| Class | Value | PreemptionPolicy | Intent |
|---|---|---|---|
| `low` | 100 | Never | Background work; evictable, won't preempt others |
| `power` | 100 | Never | Compute-heavy but expendable (e.g. AI/ML workloads) |
| `medium` | 10000 | PreemptLowerPriority | Standard services |
| `high` | 100000 | PreemptLowerPriority | Critical services; preempts lower-priority pods |
`PriorityClass` is already in the platform project's `clusterResourceWhitelist` so no project policy changes were needed.
## Test plan
- ArgoCD syncs `platform-priority-classes` successfully
- `kubectl get priorityclasses low power medium high` shows all four classes
Reviewed-on: #174
unkinben
ede25a3858