[ScottishTapWater]

Summary

• Return double when dividing quantities with matching dimensions, using a core generic operator.
• Generate double-returning multiplication operators when operand dimensions cancel.
• Carry the resulting scalar through nested expressions and inferred locals for subsequent quantity arithmetic.
• Avoid generating dimensionless quantity aliases.

Verification

• Tests written before implementation.
• All 474 tests pass: 314 core, 159 Roslyn, and 1 packaged-consumer integration test.
• Build, formatting, and diff checks pass.
• Independent production and test reviews completed twice, including test ownership and class responsibility checks; no outstanding findings.