v0.6.2

Added

• Support multiplication and division between Quantity and Factor or SymbolicConstant in both operand orders. Multiplication and right-hand division preserve the magnitude and its type, combining the exact factor with the unit's scale; left-hand division takes the reciprocal magnitude and scales the reciprocal unit. Ordinary numeric operands continue to operate on the magnitude.
• Preserve generic magnitude types in the corresponding public type hints, with runtime and static regression coverage for exact scaling and reciprocal operations.

Changed

• Combine the compact exact scale and formal units in ScaledUnit string output, grouping denominator factors into one product, such as J⋅s/(2⋅π).
• Display quantities with scaled units using the combined product and multiplication dots between adjacent numeric factors, such as 3⋅60⋅s, without evaluating the exact scale. String output remains readable display rather than parser input; repr() retains reconstructible state.
• Document exact-factor quantity arithmetic and the distinction between a symbolic expression such as SI.h / (2 * PI) and predefined SI.hbar, which continues to expose its numerical value in ordinary J*s units.