Add a WordPress Playground preview blueprint.

[johnjamesjacoby]

bbPress would benefit from a Plugin Directory preview that opens a working example forum, with a topic and reply, instead of asking a visitor to configure an empty WordPress installation.

Add a reviewed blueprint to canonical source, provisionally at .wordpress-org/blueprints/blueprint.json, and document its separate deployment to Plugin SVN assets/blueprints/blueprint.json. This file is directory preview metadata and should not be included in the plugin ZIP.

The preview should install the current stable bbPress release, activate a known-compatible classic theme, create a small set of clearly labeled sample forum content using bbPress APIs, and land on the populated forum. Visitors should be able to explore the front end and try creating a topic and reply in the temporary site.

Things to verify:

• Validate the blueprint against the current Playground schema.
• Confirm bbPress activates and its forum/topic/reply relationships and counts work with Playground's SQLite integration.
• Verify the forum index, topic, and reply forms render and work with the selected theme.
• Use disposable sample content only, without external accounts, credentials, or mail dependencies.
• Test the Plugin Directory's committer-only Test Preview before requesting approval to make the preview public.
• Document the canonical source location, separate Plugin SVN asset deployment, and the Plugin Directory Advanced-page opt-in.

The selected theme, landing page, sample content, and any required compatibility fixes should be reviewed on this ticket before enabling a public preview. Do not copy GlotPress's plugin-specific compatibility shims without a bbPress reproduction demonstrating that they are needed.

References:
​https://developer.wordpress.org/plugins/wordpress-org/previews-and-blueprints/
​https://github.com/GlotPress/GlotPress/blob/develop/.wordpress-org/blueprints/blueprint.json

[johnjamesjacoby]

In 7443:

Build/Test: add a WordPress Playground preview.

Add a canonical blueprint that installs bbPress and Twenty Twenty-One, creates a sample forum, topic, and reply with bbPress APIs, and opens the populated forum. Test the exact release build with the Playground CLI and SQLite.

Update the WordPress.org deployment workflow to copy the reviewed blueprint to Plugin SVN assets without including it in the bbPress ZIP.

In trunk, for 2.7.

Fixes #3676.

[johnjamesjacoby]

In 7444:

Build/Test: add a WordPress Playground preview.

Add the canonical bbPress preview blueprint and test the exact 2.6 release build with the Playground CLI and SQLite. Keep the blueprint out of the bbPress ZIP so it can be deployed separately as a Plugin Directory asset.

In 2.6, for 2.6.16.

See #3676.