Commit build assets for Playground and direct GitHub installs

Remove build/ from .gitignore and commit compiled JS/CSS so the
plugin works when loaded directly from the repository.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: dd32

.gitignore

@@ -1,6 +1,5 @@
 node_modules/
 vendor/
-build/
 *.log
 package-lock.json
 composer.lock

build/index-rtl.css

@@ -0,0 +1 @@
+<?php return array('dependencies' => array('react-jsx-runtime', 'wp-api-fetch', 'wp-components', 'wp-core-data', 'wp-data', 'wp-editor', 'wp-element', 'wp-i18n', 'wp-plugins'), 'version' => 'e44cf7ba85b1a87d62e8');