Implement Flutter blog and integrate old articles

[schultek]

Implements the Flutter Blog as part of the marketing site using Jaspr.

• Blog content is located at sites/www/content/blog.
• Authors are defined in sites/www/content/blog/authors.yaml.

Preview: https://flutter-dev-230821--www-pr13558-feat-blog-aajb5l2g.web.app/blog

Contributes to #13507

[flutter-website-bot]

Staged preview of the updated docs.flutter.dev site (updated for commit e471176):

https://flutter-docs-prod--docs-pr13558-feat-blog-drugp8f0.web.app

[flutter-website-bot]

Staged preview of the updated flutter.dev site (updated for commit e471176):

https://flutter-dev-230821--www-pr13558-feat-blog-aajb5l2g.web.app

[kjxbyz]

To be honest, I don't like blog systems without comment features.

[parlough]

To be honest, I don't like blog systems without comment features.

Thanks for the feedback! Once our blogs are both migrated and given some time in production, depending on community feedback, we might consider investigating support for comments and/or reactions. It requires additional planning, work, and process due to involving user data, so we won't be including support as part of this initial implementation.

In the mean time, blog posts can be (and often are) discussed on some of the great Flutter communities or on social media.

[parlough]

Thanks for the hard work on this @schultek!

Just commenting a few issues, notes, and ideas from our discussion so they don't get lost:

• Flip visual hierarchy of multiple authors (first highest)
• Slightly increase spacing of multiple author icons, so more of each one shows.
• Fix <YoutubeEmbed>, perhaps by setting up lite-youtube script like the docs site.
• Combine author yaml files into a single authors.yaml at the root of the blog/ directory.
• Remove unused fields from author yaml entries.
• Drop shadow of navbar is missing on blog pages. Seems we should keep it (or something similar) for clarity.
• Switching categories on the blog home page changes the query parameters and the page's contents. Using the browser back buttons changes the query parameters but the page contents don't update.
• Adjust available categories, make them required, and review each post to ensure it has an accurate one. (b4f55b6)

Questions:

• Should we hide the site banner like we did on the Dart blog?

[sfshaza2]

Looks great!

[schultek]

@parlough About these new github links:

When I created the list of authors, I manually went through all of them and only included github links for those that appear to have an active prescense on Github. If someone has an account that doesn't do anything I left it out. I don't want to link to peoples old/inactive accounts, that has no value.

(Referring to 80b831b)

[gemini-code-assist]

Code Review

This pull request implements a new blog system, adding several UI components, data models, and Atom feed generation. It also updates the site layout to include improved social media meta tags and adds necessary dependencies for internationalization and XML processing. The code review identified several critical runtime issues, specifically regarding YAML map parsing, frontmatter date handling, and page filtering logic that could cause build crashes. Additionally, a null-safety improvement for the clipboard API was suggested. All review comments are actionable and address potential stability and safety issues; therefore, no comments were removed.