What would you like to be added:

A new DisaggDeployment CRD that manages two LeaderWorkerSets (prefill + decode) as a single logical unit, with coordinated rolling updates and
service orchestration.

Why is this needed:

Disaggregated LLM inference (prefill/decode separation) requires coordinating two LeaderWorkerSets. Currently users must manually manage both
resources and handle rolling updates across them, which is error-prone and complex.

Completion requirements:

• DisaggDeployment CRD with prefill and decode side configurations
• Two-dimensional coordinated rolling updates across both sides
• Automatic Service creation when both sides are ready

This enhancement requires the following artifacts:

• KEP
• Implementation
• Docs update