[robelsust]

Description

In block.json, block metadata fields like style, editorStyle, and viewStyle accept file paths via the file: prefix (e.g. "style": "file:./style.css"). Build tools such as @wordpress/scripts and Webpack generate adjacent .asset.php files containing automated cache-busting hashes/versions and dependencies.

While register_block_script_handle() and register_block_script_module_id() detect and load adjacent .asset.php files to extract custom handle names, dependencies, and versions, register_block_style_handle() previously did not look for an .asset.php file, hardcoding dependencies to array() and ignoring asset versions or custom handles.

This PR adds asset file support to register_block_style_handle(), mirroring the implementation from register_block_script_handle():

1. Detects and loads adjacent [style-file].asset.php files for stylesheets defined in block.json.
2. Allows custom style handle names via the 'handle' key in the asset file.
3. Automatically passes dependencies defined in the asset file via 'dependencies' to wp_register_style().
4. Uses the asset file's 'version' (if provided) for cache-busting, falling back to SCRIPT_DEBUG filemtime or block metadata version when omitted.

Follows up on Gutenberg issue WordPress/gutenberg#56838.

Testing Instructions

1. Run PHPCS across modified source, test, and fixture files:
   vendor/bin/phpcs src/wp-includes/blocks.php tests/phpunit/tests/blocks/register.php tests/phpunit/data/blocks/notice/shared-style.asset.php tests/phpunit/data/blocks/notice/shared-style.css
   Expected: 0 errors, 0 warnings.
2. Run single site and multisite PHPUnit tests:
   vendor/bin/phpunit tests/phpunit/tests/blocks/register.php
vendor/bin/phpunit -c tests/phpunit/multisite.xml tests/phpunit/tests/blocks/register.php
   Expected: All 74 tests (248 assertions) pass cleanly.
3. Verify all block unit tests pass:
   vendor/bin/phpunit --group blocks
   Expected: All 666 tests pass cleanly.

Use of AI Tools

AI assistance: Yes
Tool(s): Antigravity
Model(s): Gemini
Used for: Analyzing register_block_style_handle vs register_block_script_handle, drafting unit test cases and fixtures. Implementation and test executions were reviewed and verified locally by robelsust.

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