chore: release 1.1.2

[firestar300]

Bump version across all configuration files and update the WordPress.org Playground blueprint.

This release fixes a potential fatal error in the Playground by using a nowdoc for the mu-plugin generation, ensuring the iframe allowlist PHP is syntactically valid.

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Note

Low Risk
Low risk release/metadata update; functional change is limited to the WordPress.org Playground demo blueprint’s mu-plugin generation and does not affect production plugin runtime.

Overview
Bumps the plugin to v1.1.2 across plugin metadata (blockparty-iframe.php, package.json, block.json, readme.txt, .plugin-data) and updates release notes.

Fixes the WordPress.org Playground demo blueprint by generating the iframe wp_kses_allowed_html mu-plugin via a nowdoc (avoiding broken PHP/fatals) and points the blueprint install ref to tag 1.1.2.

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