Implement the proposed bench metric vocabulary and unit-aware report syntax from /home/steven/projects/vargalabs-workspace/tasks/bench-metric-vocabulary-and-reporting-syntax.md. Scope: add bench::runtime, bench::throughput, bench::rate, bench::latency with typed bench::units quantities, compile-time display-unit constraints via bench::unit{...}, sensible defaults, result metadata suitable for stdout/CSV/JSON/SVG reports, and focused tests/examples. Preserve include/units.hpp style and avoid unrelated formatting changes. Base: staging, PR target: staging.
Implement the proposed bench metric vocabulary and unit-aware report syntax from /home/steven/projects/vargalabs-workspace/tasks/bench-metric-vocabulary-and-reporting-syntax.md. Scope: add bench::runtime, bench::throughput, bench::rate, bench::latency with typed bench::units quantities, compile-time display-unit constraints via bench::unit{...}, sensible defaults, result metadata suitable for stdout/CSV/JSON/SVG reports, and focused tests/examples. Preserve include/units.hpp style and avoid unrelated formatting changes. Base: staging, PR target: staging.