refactor(fortal): consolidate base button state styling

[leoafarias]

Description

Consolidates duplicated Fortal Button and IconButton visual-state definitions behind their shared Radix BaseButton boundary while retaining each component's geometry and styler adapter. It also replaces the Checkbox, Radio, and TextField effect-layer pass-through helpers with direct RemixBoxEffectLayerMix construction. Characterization coverage now compares every BaseButton variant across contrast and interaction states, including focus precedence and classic pressed offsets; package analysis and all 378 remix_fortal tests pass.

Related Issues

None.

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Checklist

Note: Updating the pubspec.yaml and CHANGELOG.md is not required. These are handled automatically during the release process.

• My PR includes unit or integration tests for all changed/updated/fixed behaviors.
• I have updated or added relevant documentation (doc comments with ///).
• I am prepared to follow up on review comments in a timely manner.

Breaking Change

Does this PR require users of the package to manually update their code?

• Yes, this is a breaking change.
• No, this is not a breaking change.