feat: Add priority field to Flavor

<!-- Please only use this template for submitting enhancement requests --> **What would you like to be added**: ```bash apiVersion: llmaz.io/v1alpha1 kind: OpenModel metadata: name: opt-125m spec: familyName: opt source: modelHub: modelID: facebook/opt-125m inferenceConfig: flavors: - name: h800 priority: 5 # higher priority nodeSelector: karpenter.k8s.aws/instance-gpu-name: h800 limits: nvidia.com/gpu: 4 - name: h100 priority: 4 nodeSelector: karpenter.k8s.aws/instance-gpu-name: h100 limits: nvidia.com/gpu: 4 - name: a100 priority: 3 nodeSelector: karpenter.k8s.aws/instance-gpu-name: a100 limits: nvidia.com/gpu: 4 - name: a20 priority: 2 nodeSelector: karpenter.k8s.aws/instance-gpu-name: a20 limits: nvidia.com/gpu: 4 - name: t4 priority: 1 # lower priority nodeSelector: karpenter.k8s.aws/instance-gpu-name: t4 limits: nvidia.com/gpu: 4 ``` **Why is this needed**: When multiple flavors are defined for a model, there is currently no explicit way to control their matching order during scheduling. The scheduler uses the order defined in the list, which may not reflect the intended preference. https://github.com/InftyAI/scheduler-plugins/blob/685a4d9f8a769f7f5634a6680f374a05c72823cd/pkg/plugins/resource_fungibility/resource_fungibility.go#L228-L248 **Completion requirements**: This enhancement requires the following artifacts: - [ ] Design doc - [ ] API change - [ ] Docs update The artifacts should be linked in subsequent comments.