Migrate the site infrastructure to Jaspr and Jaspr Content

[parlough]

Staged: https://flutter-docs-prod--pr12548-feat-jaspr-migration-kz7c0jfj.web.app/

Migrates the site from being built with JS/TS, Node, and 11ty to being built with purely Dart, Jaspr, and Jaspr Content.

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As part of this work, the dash_site bash script has been removed from the root of the repository.

After the removal, you can access the site tooling, including building and staging with dart run dash_site <command> from anywhere within the repository workspace. If you still want a shorter command, you can add an alias for dart run dash_site in your shell, such as dst.

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Staged: https://flutter-docs-prod--pr12548-feat-jaspr-migration-kz7c0jfj.web.app/

Resolves #12405
Fixes #12590

[flutter-website-bot]

Visit the preview URL for this PR (updated for commit 70094ef):

https://flutter-docs-prod--pr12548-feat-jaspr-migration-kz7c0jfj.web.app

[parlough]

@schultek Can you take a look at why the llms.txt file is being rendered as HTML rather than being passthrough rendered? Perhaps I configured the rawOutputPattern incorrectly or misunderstood it. I appreciate the help!

[parlough]

Thank you both for taking a look and the feedback!

Addressing each of the points raised by @sfshaza2 with resolutions and a few questions:

On the front page, the What's New in Flutter video is smaller on the staged site. Can we restore the OG size?

I've fixed this! Now the YouTubeEmbed component supports a fullWidth attribute that I've also added to that embed :D

There is additional white space on the left side (following the sidenav) on new pages that are missing the On this page column from the new page. OG page. New page. Other pages do have the On this page column, so did I happen to select one where it's turned off?

The widget catalog pages happen to be pages where I turned off the TOC in this PR, so I believe this difference is to be expected. If you notice it elsewhere though, do please let me know :)

OK, hang in there. Expand the Testing & debugging menu in the sidenav. Then, under Testing, select Overview. It brings up the page. Select Overview again. And again. On the OG page, things seem good. On the new page, every time, you select Overview, the sidenav jumps (as if it's missing a test to see if the page is already up).

Nice catch. Fixed! Scrolling to the active entry in the sidenav should happen before page load finalizes now.

On the new site (on the same page as in the previous bullet), there are extra blank lines in the top two bulleted lists, but not in the last bulleted list. A rather weird inconsistency.

I see this inconsistent spacing on the old/live version but not on the new version. Does that match what you're seeing? If there's still an issue though, can you send a screenshot?

There seems to be a difference in font. OG page. New page. Scroll to the Handling all types of headers header on each pages. The font is thinner and narrower on the new site, making it harder to read.

I can't seem to reproduce this. The fonts look the same when I overlay the pages. Can you try hard refreshing each page and let me know if you still notice differences? And send a screenshot of both. Thanks!

Have we run the updated pages through accessibility testing?

Good idea, thanks! I went ahead and did so and I fixed the one regression that came up as well as fixed a pre-existing issue.

[craiglabenz]

@parlough You asked us to point out pages with TOC differences other than the widget catalog, so while I'm 99% sure you already know this and it's probably expected, I'll do my due diligence and flag that I see the TOC missing on the new site's homepage, but present on the old site's homepage.

[sfshaza2]

lgtm

[parlough]

Thanks for all the hard work and help here @schultek and thanks everyone else for the great feedback and help along the way :D