[JEWEL-1069] Implement slim button

[wellingtoncosta]

Summary

This PR introduces a new button variant called SlimButton, which has both default and outlined styles and it's intended to be used in toolbars and space-constrained UIs. As part of the public API, there are both DefaultSlimButton and OutlinedSlimButton, following the pattern for other button variants.

A slim button section was added to the sample app, showcasing how it looks like.

Screenshot

Release notes

New features

• Added a new button variant called SlimButton, which has both DefaultSlimButton and OutlinedSlimButton styles

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Note

Adds a compact button variant for space-constrained UIs.

• New DefaultSlimButton and OutlinedSlimButton components with reduced padding/height (24dp) and toolbar-friendly metrics
• Introduces ButtonMetrics.slim and ButtonStyle.Slim factories in Int UI styling
• Theme plumbing: exposes defaultSlimButtonStyle/outlinedSlimButtonStyle via JewelTheme, composition locals, and DefaultComponentStyling; integrates into IntUi themes and Swing bridge readers
• Showcase app: adds a “Slim buttons” section demonstrating both variants

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