Define bounded CPU performance evidence

[itdevwu]

Goal

Define how CPU counters or samples relate to an endpoint-to-endpoint measurement before adding a collector that could imply unsupported causality.

Acceptance criteria

• The protocol distinguishes event latency, interval counters, and statistical samples.
• Supported perf events, scope, multiplexing, sampling error, and collection bounds are explicit.
• Correlation quality never describes sampled CPU activity as exact causality.
• A minimal collector and deterministic fixture prove the chosen contract.
• No daemon or persistent session service is introduced.