Replace Naive UI number input and slider primitives

[nighca]

Background

As part of #3017, another sub-area is numeric and range-like input.

Current dependency points include:

• src/components/ui/UINumberInput.vue
• src/components/ui/UISlider.vue

Problem

These controls still depend on naive-ui primitives and styling assumptions:

• UINumberInput wraps NInputNumber
• UINumberInput relies on deep selectors against naive-ui input DOM/class names
• UINumberInput also works around autofocus behavior manually
• UISlider is built on NSlider
• downstream call sites also style against naive-ui slider DOM/class names in some places

These controls should be migrated as a pair because they both represent scalar value editing and may benefit from aligned UX behavior.

Goal

Replace the remaining naive-ui dependency in numeric and range-like inputs with internal implementations.

Scope

• replace NInputNumber in UINumberInput
• replace NSlider in UISlider
• preserve current features such as min/max, prefix/suffix slots, autofocus, custom thumb rendering, color variants, and dragend vs input update behavior
• reduce styling and DOM coupling to naive-ui
• align behavior with existing XBuilder expectations in places that consume numeric controls heavily

Notes

This issue is intentionally grouped around scalar value controls. Text input and boolean/choice controls are tracked separately.