feat(ui-components): add Signature and FunctionSignature components

[canerakdas]

Description

Adds new Signature and FunctionSignature components for rendering API function signatures with support for nested parameters, return types, and optional attributes.

Ref: nodejs/doc-kit#587
Figma: https://www.figma.com/design/a10cjjw3MzvRQMPT9FP3xz/Node.js?node-id=6382-1517&t=T63PRMdf9tzlCrww-0

Validation

Related Issues

Related to nodejs/doc-kit#587

Check List

• I have read the Contributing Guidelines and made commit messages that follow the guideline.
• I have run pnpm format to ensure the code follows the style guide.
• I have run pnpm test to check if all tests are passing.
• I have run pnpm build to check if the website builds without errors.
• I've covered new added functionality with unit tests if necessary.

[vercel]

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[github-actions]

👋 Codeowner Review Request

The following codeowners have been identified for the changed files:

Team reviewers: @nodejs/nodejs-website

Please review the changes when you have a chance. Thank you! 🙏

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.14%. Comparing base (377f606) to head (8908ad4).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8660      +/-   ##
==========================================
+ Coverage   75.08%   75.14%   +0.06%     
==========================================
  Files         104      104              
  Lines        9098     9098              
  Branches      315      315              
==========================================
+ Hits         6831     6837       +6     
+ Misses       2265     2259       -6     
  Partials        2        2              

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[avivkeller]

Love it!

(Note on the Figma: I moved the node a bit closer to the rest of the other nodes, just to make it easier to find)

[Copilot]

Pull request overview

Adds new Signature and FunctionSignature UI components to render API-style function signatures (including nested parameters, return types, and optional markers), plus Storybook stories and styling.

Changes:

• Introduce Common/Signature (root + item + header subcomponents) with CSS modules.
• Add Containers/FunctionSignature wrapper to render signature trees from data.
• Bump @node-core/ui-components version to 1.6.1.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
packages/ui-components/src/Containers/FunctionSignature/index.tsx	Renders a signature tree from an items definition array.
packages/ui-components/src/Containers/FunctionSignature/index.stories.tsx	Storybook coverage for nested/return/type-only signature examples.
packages/ui-components/src/Common/Signature/index.tsx	Public Signature component that switches between root vs item rendering.
packages/ui-components/src/Common/Signature/index.stories.tsx	Storybook examples for Signature.
packages/ui-components/src/Common/Signature/SignatureRoot/index.tsx	Section wrapper + title rendering for grouped signature blocks.
packages/ui-components/src/Common/Signature/SignatureRoot/index.module.css	Styles for the signature block container and title area.
packages/ui-components/src/Common/Signature/SignatureItem/index.tsx	Renders a single signature row (header + description + children).
packages/ui-components/src/Common/Signature/SignatureItem/index.module.css	Styles for items, nested children layout, and return highlighting.
packages/ui-components/src/Common/Signature/SignatureHeader/index.tsx	Renders name/type header, optional marker, and return icon.
packages/ui-components/src/Common/Signature/SignatureHeader/index.module.css	Header/type styling for signature rows.
packages/ui-components/package.json	Version bump to publish the new components.

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[avivkeller]

This PR needs to be re-created for Vercel to deploy it