Fix modifier ordering and interpolation endpoints

[leoafarias]

Problem

Two correctness problems affect widget modifiers:

1. MixScope.orderOfModifiers is publicly exposed, inherited, and tracked as a modifierOrder aspect, but normal WidgetModifierConfig.resolve(context) does not read it. As a result, configuring modifier order at the scope has no effect on rendering.
2. ModifierListTween iterates only the target list. It removes begin-only modifiers immediately and, for target-only modifiers without a neutral default, can include the modifier at t = 0 but omit it at t = 1. Animated results therefore fail to reach the requested endpoint.

Expected behavior

Modifier ordering should use this precedence:

style-local WidgetModifierConfig order
  > nearest MixScope modifier order
  > package default order
  > remaining configured types in stable order

ModifierListTween must satisfy lerp(0) == begin and lerp(1) == end for every membership case. For modifiers present on only one side, interpolate through a genuine neutral modifier where one exists; otherwise snap in or out at the documented midpoint in the correct direction.

Acceptance criteria

• MixScope.orderOfModifiers changes normal style-widget rendering.
• Style-local modifier order overrides the inherited scope order.
• Modifier-order dependencies subscribe precisely to the modifierOrder aspect.
• Tween endpoints exactly match the requested begin and end lists.
• Additions and removals animate correctly both with and without neutral defaults.
• Reset modifiers remain filtered and never reach rendering or interpolation.
• Regression coverage includes resolved modifier order, rendered wrapper nesting, and the interpolation membership matrix.