[ScottishTapWater]

Summary

• Add <, >, <=, and >= for quantities with matching dimensions.
• Add static Abs, Min, Max, and Clamp helpers, available through quantity aliases such as Current.Clamp(value, min, max).
• Preserve ordinary double comparison and Math helper semantics, including NaN. Keep the runtime compatible with netstandard2.0.

Verification

• Independent C# production and test reviews completed with no blocking findings.
• Solution build: zero warnings and errors.
• Full suite: 929 passed, including package integration tests.
• Focused formatting verification and git diff --check passed.