Issue 20: FluxRadio — Refactor

[abdelrzz9]

Est: 4 hrs · Deps: Issue #1, #2, #8

Requirements:

• Create FluxRadioGroup for managing radio state
• Change FluxSize.md → FluxRadioSize enum
• Accept Widget? for label
• Integrate FluxPressable
• Add FluxRadioTheme extension
• Add Semantics with Radio role
• Support controlled + uncontrolled
• Animate selected indicator
• Add debugFillProperties

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