Add regional affinity to multi-cluster function autoscaling

[nv-lacm]

Description

Improve multi-cluster scale-up placement for all NVCF workloads. Prefer an eligible cluster in the same region as current demand. When that region is unavailable, select the nearest eligible region using a documented proximity policy.

Customer placement constraints and existing health, capacity, quota, and instance-type checks remain authoritative. Dynamo Planner continues to manage pods within an NVCF instance; NVCF owns instance creation and cross-cluster placement.

Definition of Done

• Scale-up can target a specific eligible cluster.
• A same-region cluster is preferred when available.
• Cross-region fallback uses a deterministic, documented proximity policy.
• Explicit customer placement constraints override the default preference.
• Missing region metadata and unavailable capacity have documented fallback behavior.
• Single-cluster behavior is unchanged.
• Logs and metrics identify the selected cluster, policy, and fallback reason.
• End-to-end tests cover same-region selection, nearest-region fallback, customer overrides, missing metadata, and no eligible cluster.
• Documentation explains the NVCF and Dynamo Planner responsibility boundary.

Resources (optional)

• Function autoscaler integration
• NVCF public roadmap

---

By submitting this issue, you acknowledge that you are an assigned member of the NVCF development team and agree to follow our code of conduct and our contributing guidelines.