docs: real-world integration examples (Next.js, plain HTML, marketplace storefront) in the docs playground

[aguilar1x]

Context

Issue #20 improved SDK onboarding docs, but there are still no runnable, realistic example apps showing Connect integrated into an actual storefront pattern — the gap most new integrators hit first.

Scope

• Three example integrations added to apps/docs's playground: a Next.js app using connect-react, a plain static HTML page using connect-elements, and a marketplace-style storefront (multiple products, one checkout) demonstrating the SDK in a realistic layout.
• Each example is runnable locally (npm run dev from its own folder) and deployed/linked from the docs playground.
• Docs page walking through each example's source, referencing the onboarding guide from Improve SDK developer onboarding and integration flow #20.

Acceptance criteria

• All three examples run locally with a documented one-command setup.
• Each example is reachable and interactive from the docs playground, not just linked source code.
• The marketplace example demonstrates at least two distinct products checking out through the same integration.

[ghost-cy829]

I’m a full-stack software developer experienced in both enterprise applications and Web3 projects, with four hackathon wins and hands-on work across frontend, backend, APIs, databases, and blockchain integrations. I will first review the issue and existing codebase, then implement a clean, well-tested solution and submit a clear PR within the agreed timeline. Kindly assign.

[zeemscript]

Hello, I’ve gone through the requirements and I’m confident I can implement a proper solution that matches the acceptance criteria. Kindly assign this issue to me.

[Okorie2000-code]

Hi Maintainer,

I'd like to work on this issue. I have experience with Next.js, SDK integrations, and technical documentation, and I can submit a clean PR within 48 hours.

[happyboy24]

CAN I PLEASE WORK ON THIS PLEASE

[Davichi-1]

Hello! I have experience in full-stack and blockchain development, and I'd like to take on this issue. I can provide a clean, maintainable solution. Please assign it to me if it's still open.

[abufauzahn]

Hi! I've carefully reviewed the entire task description and fully understand the requirements and expected outcome.
I have experience working on similar tasks and I'm confident I can complete this within about an hour. I'd be happy to take ownership of this issue and submit a clean, well-tested solution promptly.
If it's available, please assign it to me. Thank you!

[Primex-hub]

I will love to fix this issue

[Bran18]

Hi! I'd love to work on this issue.

I'm a full-stack developer from Costa Rica with experience building production applications using TypeScript, React, Next.js, AI, and Stellar. I'm an active open-source contributor and maintainer of several projects, and I enjoy collaborating with teams to deliver high-quality, well-tested code.

I took a look at the issue, and I'm confident I can implement it while following the project's existing architecture and coding standards. I'd be happy to take this one on.

Thanks for your consideration!

[grantfox-oss]

🦊 GrantFox — @Bran18 has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #43)
2. Your PR will be reviewed by the PACTO-LAT maintainers

Good luck! Track your progress on GrantFox.