cold-start controls (warm pools, min replicas, idle policies)

[ashupednekar]

Summary

Add explicit cold-start controls and warm-pool strategies.

Motivation

Latency-sensitive workloads need predictable startup behavior and configurable cost/performance tradeoffs.

Proposal

• Min warm instances per language/project/function.
• Keep-warm pools and prefetch hooks for hot paths.
• Idle shutdown policy tiers.
• Cold-start telemetry and SLO reporting.

Acceptance criteria

• Operators can configure warm capacity and idle policy.
• Cold-start latency is measurable and visible.
• Keep-warm behavior integrates with deprovision logic.