## What this PR does
Adds the cozystack-scheduler as an optional system package, vendored
from https://github.com/cozystack/cozystack-scheduler. The scheduler
extends the default kube-scheduler with SchedulingClass-aware affinity
plugins, allowing platform operators to define cluster-wide scheduling
constraints via a SchedulingClass CRD. Pods opt in via the
`scheduler.cozystack.io/scheduling-class` annotation.
The package includes:
- Helm chart with RBAC, ConfigMap, Deployment, and CRD
- PackageSource definition for the cozystack package system
- Optional inclusion in the platform system bundle
### Release note
```release-note
[cozystack-scheduler] Add cozystack-scheduler as an optional system
package. The custom scheduler supports SchedulingClass CRDs for
cluster-wide node affinity, pod affinity, and topology spread constraints.
```
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Added cozystack-scheduler component as an optional system package.
* Introduced SchedulingClass custom resource for advanced scheduling
configurations.
* Scheduler supports node affinity, pod affinity, pod anti-affinity, and
topology spread constraints.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Andrei Kvapil
941fb02cd1