[Benchmark]: Measure governance query and read performance

[rian-be]

Summary

Benchmark governance query and read performance so request, approval, and decision lookups stay visible over time.

Goal

Measure the overhead of governance read paths that list requests, approvals, and decisions for operational use cases.

Problem

Governance already models query-oriented stores and read views, but those paths are not benchmarked as a dedicated runtime surface.

Without a benchmark for governance query behavior, changes in request listing, approval lookup, or decision projection can quietly add overhead without being visible in runtime measurements.

Scope

• Benchmark listing pending governance requests
• Benchmark listing pending approvals
• Benchmark reading recent governance decisions or execution outcomes
• Keep the benchmark focused on governance read paths rather than write-side persistence internals
• Reuse existing governance benchmark helpers where they already exist
• Make scenario names explicit about the query path being measured

Design Expectations

• The benchmark should measure a real read flow rather than a toy loop.
• Request, approval, and decision reads should remain visible where possible.
• Helper code should stay local to the benchmark project.
• Scenario names should make the query path obvious.

Suggested Measurements

• pending request list lookup
• pending approval queue lookup
• recent decision or execution outcome lookup

Acceptance Criteria

• Governance query and read performance is benchmarked as a distinct governance scenario
• Pending request read cost is visible in the benchmark results
• Approval queue or decision read cost is visible in the benchmark results
• The benchmark remains centered on governance runtime behavior

Non-Goals

• This issue does not change governance runtime behavior
• This issue does not add provider-specific persistence benchmarks
• This issue does not optimize query paths prematurely
• This issue does not add full integration or load testing

Notes

This issue is a child of the governance benchmark umbrella #73.