fix: align number input icon rendering

[Saithej2k]

Summary

• Render ui-number-input inner icons through Vuetify slots so right-side inner icons appear alongside the number controls.
• Remove extra local inner-icon margins so number input spacing matches text inputs.

Testing

• git diff --check
• npx eslint ui/src/widgets/ui-number-input/UINumberInput.vue
• npm run build

Closes #2022