feat: add mc-collapsible component

[kpadams94]

Summary

• add a behavior-only McCollapsible wrapper using Base UI primitives
• register the component and its generic demo in the registry
• add documentation and Storybook coverage for playground, default-open, and disabled states

Validation

• formatting, TypeScript, and ESLint checks pass
• documentation, internal registry, and external registry builds pass
• Storybook and Next.js production builds pass
• verified open/close behavior in all five themes using light and dark modes

Closes #54

[hexxt-git]

@kpadams94 thanks for the contribution, the code looks clean but there are some major blockers before merging this.

1. checkout the issue #54 for the Figma design link. you should be following that rather than a custom design. there are missing icons

2. your component ships unstyled and the demo uses overrides that using render={} and className={} props. that is contrary what mcoli-ui library is going for (checkout contributing.md)

3. update the progress in the issue #54 since you're assigned. you can do this just by clicking the check-mark for what you id

4. move the collapsible component out of "coming soon" section

[Adel2411]

@kpadams94 nice structuring of the work, you fit the patterns of the project perfectly
You can take a look at @hexxt-git remarks

• it would be even better to make the mc-collapsible-demo.tsx fitting the figma (even with basic HTML Tags and className its okey since its behavioral component) so it becomes copy-paste ready in the docs
• Also make sure when you finish to send screenshots of the demo component to take a look at the result

Thanks for contributing

[kpadams94]

Thanks for the feedback — I pushed commit 771dc50 addressing the requested changes:

• updated mc-collapsible-demo.tsx to match the Figma design, including the ChevronsUpDown icon and the 350×78 closed / 350×170 open dimensions
• kept the distributed component behavior-only, with the Figma styling in the copy-paste demo
• updated Storybook to reuse the demo and removed the duplicate render implementation
• moved mc-collapsible out of the “Coming Soon” section
• verified the registry build, formatting, TypeScript, lint, Storybook and Next.js production builds, plus all five themes in light and dark modes

I was unable to mark the checkboxes in issue #54 because GitHub did not give me permission to edit the issue. All checklist items have been completed; could a maintainer please update them?

Closed and open screenshots:

[Adel2411]

@kpadams94 everything seems aligned with the issue and is ready to merge!

thanks for the contribution, let me know if you are looking forward to contribute on other upcoming issues