Alternative Progressive Delivery for Deployment in OpenKruise Rollout

The current OpenKruise Rollout implementation for Deployment progressive delivery mutates the updateStrategy to Recreate, creating a dangerous risk window: if the Deployment is not properly paused during rollout disable, removal, or controller crash, all pods could be simultaneously recreated, causing a service outage (ref openkruise/rollouts#305). This project implements a safer alternative by keeping the Deployment strategy as RollingUpdate and leveraging minReadySeconds and progressDeadlineSeconds to control the delivery pace. Updated pods remain in a "Ready but not Available" state, giving the Rollout controller precise batch-level control without the catastrophic failure mode of the current approach. Deliverables: 1. A new minReadySeconds-based progressive delivery implementation for Deployment in OpenKruise Rollout 2. End-to-end test suite covering normal rollout, rollback, controller crash recovery, and edge cases 3. Documentation for the new deployment strategy mode