[Improvement] Combine "text" and "label" UI Stamp Option variants

### Description

The `_UI Stamp Options` subcomponent currently has separate text and label variants, which lead to some inconsistent UX when customizing UI Stamps. These could be combined into a single variant.

### Why

This would reduce the number of exposed properties on UI Stamp components, simplifying the configuration experience.

Open the Figma library and inspect the current _UI Stamp Options subcomponent, focusing on its separate text and label variants. Combine those variants into one configuration and verify that UI Stamp components expose fewer, consistent properties without losing the existing customization options.

索引モデルが issue の本文から書いたものです。