LegacyUnitRamp

The slider-unit ramp of one setting: a divisor and the largest magnitude the legacy control could produce in engine units.

In the namespace construct::settings. Declared in src/libs/libconstruct/construct/settings/ConstructSchema.hpp.

Detailed description

Zero means no ramp. The threshold is a frozen fact about a build that already shipped. Do not update it when a control's range widens: `testTheRampThresholdIsFrozen` pins each value against a literal.