A payments microservice running on Compute Engine has gradually increased its CPU utilization over the past three release cycles, driving up costs and occasionally triggering autoscaling that adds instances during peak traffic. The engineering team suspects inefficient code paths but cannot reproduce the behavior in staging, where load patterns differ. They need continuous, low-overhead visibility into which functions consume the most CPU and heap in the live production environment, correlated across releases, without redeploying instrumented builds each time. Which Google Cloud Observability capability should the architect recommend?