chore: add WordPress Playground blueprint

[firestar300]

Adds a blueprint.json configuration to allow users to test the plugin in a WordPress Playground environment and includes a "Test with WordPress Playground" badge in the README.

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Note

Low Risk
Low risk: documentation/support tooling only, with no runtime code changes. Main risk is the blueprint.json becoming stale (e.g., pinned plugin tag/version).

Overview
Adds a WordPress Playground entrypoint so reviewers/users can launch a preconfigured WP instance that auto-installs/activates the plugin via a new blueprint.json.

Updates README.md to include a “Test with WordPress Playground” badge linking to that blueprint.

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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Blueprint hardcodes tag instead of tracking main branch

Medium Severity

The blueprint.json is served from the main branch (as linked by the README badge), but it hardcodes "ref": "1.0.4" with "refType": "tag" for the plugin install. This means the "Test with WordPress Playground" badge will always install the 1.0.4 release rather than the current state of main. After any future version bump, the blueprint silently becomes stale and won't reflect the latest code, defeating the purpose of a live testing badge.

Additional Locations (1)

• README.md#L2-L3