Fix hidden Switch label spacing

[czarandy]

Summary

• keep screen-reader-only Switch labels out of flex flow when no description is visible
• ignore spread spacing when there is no visible label content, keeping the row control-sized
• preserve the existing visible-description layout and accessible label association
• add default/spread regression coverage and a no-description Storybook example

Validation

• pnpm test (3,485 tests)
• pnpm typecheck
• pnpm lint
• pnpm format:check
• pnpm build
• pnpm build:storybook

Closes #571

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
silver-ui-site	Ready	Preview	Aug 25, 2026 1:50am

1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
silver-ui	Ignored	Preview	Aug 25, 2026 1:50am