Closes #7

## Changes:

- Adds an autoplay param so embedded playgrounds show something to the user instead of a black screen
- Updates the non-audio templates to skip the play button. I'm envisioning for the embedded playgrounds in the docs to follow a similar pattern? Especially if its not audio or not too intense.

I have also tried to address a timing issue. I believe its already happening in production, but seems more obvious with autoplay enabled. Occasionally throwing the following "Typescript is not registered".

We're not the only team to hit this:

- https://forum.babylonjs.com/t/ts-playground-red-banner-could-not-find-source-file-inmemory-model-1/55126/4?utm_source=chatgpt.com
- https://github.com/BabylonJS/Babylon.js/pull/11554

If I understand the Babylon playground code, they are retrying? At least the comment suggests that.

There is an open issue for Monaco Editor, but unfortunately its almost 10 years old. With "waiting skeleton" memes included. https://github.com/microsoft/monaco-editor/issues/115

Regardless, I've added a little exponential backoff that retries the client/worker. Since adding that retry code, it consistently loads. Often between 0 and 2 attempts

Fixes pathing issue created in https://github.com/excaliburjs/excalibur-playground/pull/4

I've folded in a few other changes as part of this PR:
- added the running man spritesheet asset, I figured that would be useful for the docs.
- I'm not sure where the running man came from, so no licence info.
- vertically stack the canvas and editor when embedded
- this is to support the change in the docs to be more like this https://svelte-pixi.com/api/components/animated-sprite/

On that second point (the svelte-pixi example), I am wondering if we should completely hide the toolbar and instead autoplay when embedded?

=== :clipboard: PR Checklist :clipboard: ===

- [ ] :pushpin: issue exists in github for these changes
- [ ] :microscope: existing tests still pass
- [ ] :see_no_evil: code conforms to the [style guide](https://github.com/excaliburjs/Excalibur/blob/master/STYLEGUIDE.md)
- [ ] :triangular_ruler: new tests written and passing / old tests updated with new scenario(s)
- [ ] :page_facing_up: changelog entry added (or not needed)

==================

No issue raised, but discussed here: https://github.com/excaliburjs/Excalibur/pull/3531

## Changes:

- Adds embedded mode for iframes, such as in the docs
- Embed mode hides the header and minimap
- Follows the users color preferences (typically within the OS, but can also be set via the browser)

### Light / dark mode

<img width="2440" height="1336" alt="CleanShot 2025-10-13 at 14 55 22@2x" src="https://github.com/user-attachments/assets/6de8f813-d22a-4b19-839b-32846c3b8453" />

<img width="2438" height="1394" alt="CleanShot 2025-10-13 at 14 55 34@2x" src="https://github.com/user-attachments/assets/72c822b9-4301-4588-be20-4e5277d60b2b" />

### Embedded version

<img width="2462" height="1360" alt="CleanShot 2025-10-13 at 14 56 53@2x" src="https://github.com/user-attachments/assets/7c2b3153-c756-4d0b-9a58-91d2113e834c" />




## Notes:

**Note 1** In this PR, it only checks the color preferences once on load. It then sets the monaco editor theme. It doesn't dynamically change if you toggle your OS settings, you need to refresh the page.

Its technically possible to "watch" the change of light/dark preference (e.g. [here](https://stackoverflow.com/a/57795495/614112)), but didn't feel too critical. It also raises the question of the user loosing their progress if the editor reinitialises.

**Note 2** The share button replaces the embed search param with `code=`. It can append instead, but I was on the fence if this was a good or bad thing. If the intention is to share, the user probably doesn't want the embedded version any more, so removing makes sense. Maybe?