feat(components): add underline prop to Link component

[hsadhvani]

Summary

Add an underline prop to the Link component following the MUI Link pattern. This gives consumers control over when a link is underlined.

Values:

• 'hover' (default) — underline on hover only (current behavior, no breaking change)
• 'always' — always underlined, even at rest
• 'none' — never underlined, even on hover

This addresses a need from the experimentation team where links on dark backgrounds (e.g. the experiment approval action bar) are indistinguishable from body text when semibold — and changing the link color fails contrast standards.

Changes:

• Link.tsx: Add underline as a CVA variant with always | hover | none values
• Link.module.css: Add .underlineAlways, .underlineHover, .underlineNone classes
• Link.spec.tsx: Add test for underline="always"
• Link.stories.tsx: Add UnderlineAlways and UnderlineNone stories

Usage:

<Link href="/test" underline="always">View pending change</Link>
<Link href="/test" underline="none">No underline ever</Link>

Testing approaches

• Unit tests added and passing
• Biome lint passes
• TypeScript check passes

Link to Devin session: https://app.devin.ai/sessions/e7f835e7f72f429da7490a51b5b334a2
Requested by: @hsadhvani

---

Note

Low Risk
Low risk: adds an optional styling prop to Link with a default matching existing hover-underline behavior, plus small CSS/story/test updates.

Overview
Adds an underline prop to Link ('always' | 'hover' | 'none') implemented as a new CVA variant, defaulting to 'hover' to preserve current behavior.

Updates Link.module.css with underline-specific classes, adds Storybook examples for the new options, and includes a basic unit test plus a changeset marking a minor version bump.

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[changeset-bot]

🦋 Changeset detected

Latest commit: 199af92

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@launchpad-ui/components	Minor

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[pkg-pr-new]

yarn add https://pkg.pr.new/@launchpad-ui/components@1888.tgz

yarn add https://pkg.pr.new/@launchpad-ui/icons@1888.tgz

yarn add https://pkg.pr.new/@launchpad-ui/tokens@1888.tgz

commit: 02d01e8