feat(DSYS-490): migrate TextButton to ADR-0003 and ADR-0004

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Description

Migrates the TextButton component to follow ADR-0003 (String Unions) and ADR-0004 (Centralized Types Architecture) patterns.

Changes:

1. ADR-0003 (TextButtonSize const object): Converts the TextButtonSize enum from design-system-react/src/types/index.ts into a const object in design-system-shared. Values (body-lg, body-md, body-sm, body-xs) remain identical.

2. ADR-0004 (TextButtonPropsShared): Creates a shared props type in design-system-shared with cross-platform properties (children: ReactNode, isDisabled?: boolean).

Files changed:

• packages/design-system-shared/src/types/TextButton/TextButton.types.ts — new TextButtonSize const + TextButtonPropsShared type
• packages/design-system-shared/src/types/TextButton/index.ts — new barrel export
• packages/design-system-shared/src/index.ts — exports TextButtonSize and TextButtonPropsShared
• packages/design-system-react/src/types/index.ts — removes old TextButtonSize enum
• packages/design-system-react/src/components/TextButton/* — updates all files to import from @metamask/design-system-shared
• packages/design-system-react-native/src/components/TextButton/* — types extend TextButtonPropsShared, index exports TextButtonSize
• packages/design-system-react-native/src/components/index.ts — adds TextButtonSize to exports

Related issues

Fixes: DSYS-490
Part of epic: DSYS-468 — Component ADR Migration

Manual testing steps

1. Import TextButtonSize from @metamask/design-system-react — verify it still works
2. Import TextButtonSize from @metamask/design-system-react-native — verify it now exports
3. Import TextButtonSize and TextButtonPropsShared from @metamask/design-system-shared — verify both export
4. Use <TextButton size={TextButtonSize.BodyMd}> in React — verify no TypeScript errors

Screenshots/Recordings

Before

TextButtonSize was an enum in design-system-react/src/types/index.ts, not available in shared or React Native.

After

TextButtonSize is a const object in design-system-shared, exported from all three packages. TextButtonPropsShared provides cross-platform shared props.

Pre-merge author checklist

• I've followed MetaMask Contributor Docs
• I've completed the PR template to the best of my ability
• I've included tests if applicable
• I've documented my code using JSDoc format if applicable
• I've applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

  

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