feat(crd): add deployment policy

[t0mmylam]

Add DeploymentPolicy CRD and Skyhook Reference Fields

Summary

Implements the foundational CRD types for Safe Rollouts, enabling compartmentalized interruption budgets and configurable deployment strategies.

Changes

SkyhookDeploymentPolicy CRD:

• spec.default defines budget (percent|count) and strategy for unmatched nodes
• spec.compartments[] enables per-node-class overrides with selector, budget, and optional strategy
• Three strategy types: Fixed (constant), Linear (delta increment), Exponential (growth factor)
• Full OpenAPI validation with parameter bounds and single-key sum-type enforcement

Skyhook Updates:

• Added spec.deploymentPolicy to reference a DeploymentPolicy

Next Steps

Admission webhooks, controller scope resolution, strategy implementations, and per-compartment metrics.