Add Moodle Playground demo (blueprint + README badge)

[erseco]

About this PR — Moodle Playground

Moodle Playground (source) runs a full Moodle site entirely in the browser (PHP + SQLite via WebAssembly). A blueprint.json describes how to provision plugins, users, courses and sample content so anyone can try a plugin with one click — no Docker, no local Moodle.

Current scope (simplified)

This PR now only adds:

1. blueprint.json — installs qtype_gapfill, creates a demo course with a ready-to-play quiz (“Testing Gapfill!”) showcasing drag & drop, dropdown and text-entry modes with sample questions already imported, and lands on the quiz page.
2. README.md — short “Try in Moodle Playground” section with a badge pointing at this repository’s main/blueprint.json so it works as soon as this is merged. Existing README content is otherwise unchanged.

The earlier GitHub Action / PR-preview workflow has been removed to keep the contribution small and avoid pull-requests: write and related trade-offs. See the latest comment for context.

Test plan

• Open the Playground demo from the comment and confirm Moodle boots with Gapfill installed.
• Confirm the demo quiz shows the three answer modes with sample questions.
• Confirm this PR does not add any GitHub workflow under .github/workflows/.

[bhect0]

It's great to see this pull request! Moodle Playground is epecially useful for trying out qtype plugins easily because you can skip all the configuration steps such as creating the quiz and the questions :)

Then, you also have the opportunity to create more questions manually so it's a nice way to allow all kind of users to test the plugin.

I'm very happy with the integration with Guess It: https://github.com/bhect0/moodle-qtype_guessit#try-in-moodle-playground

[marcusgreen]

Hi Héctor, I had not really heard of Moodle Playground until MoodleMootDach two weeks ago when I chatted with Guy Thomas. I have yet to experiment with it myself, but this look like a good idea.

[bhect0]

Hi Marcus! It's nice to hear that, I'm really happy to know that Moodle Playground is becoming popular step by step :)

@erseco is the creator of this super tool!

[erseco]

Thanks for reviewing the PR and for the kind words!

The original idea was to allow users to quickly test the plugin both from main through the README and directly from pull requests. That said, generating PR preview links with GitHub Actions can raise security and maintenance concerns, as happened in this review.

Would you prefer me to simplify the PR and keep only the blueprint file and the Playground link in the README? Just tell me and I will update the PR code :)

[erseco]

Hi Marcus (and thanks Héctor for the kind words earlier!),

Following up on my previous comment: I have gone ahead and simplified this PR.

The GitHub Action that auto-posted preview links on every pull request has been removed. What remains is only:

• blueprint.json — one-click demo with a ready-to-play Gapfill quiz (all three answer modes)
• README.md — “Try in Moodle Playground” badge (points at this repo so it works as soon as this is merged)

No workflow, no extra permissions, no PR auto-comments — just an easy way to try the plugin online, which is especially useful for question types as Héctor noted.

You can try the demo from this branch here:

Happy to adjust the blueprint or README wording if you would like anything different. Thanks again for considering this!

[marcusgreen]

I just clicked the Try it in Playground button, it looks very impressive. Better do my day job now though....