fix: prevent wp-edit-post from loading in the customizer block widgets editor

[faisalahammad]

Description

This fix extends the existing pagenow check for widgets.php to also cover customize.php. CoBlocks was loading the wp-edit-post script dependency in the customizer, causing a JS conflict with themes like Blocksy when WooCommerce is also active.

The editor_assets() method already strips wp-edit-post and wp-editor from script dependencies on widgets.php, but the customizer was not included in that check.

Fixes #2627

Screenshots

N/A

Types of changes

Bug fix (non-breaking change which fixes an issue)

How has this been tested?

• Code review confirmed the fix mirrors the existing widgets.php pattern exactly.
• PHP syntax check passed on both modified files.
• CodeRabbit review passed (0 findings).
• New PHPUnit test test_wp_edit_post_stripped_on_customize_php verifies wp-edit-post and wp-editor are stripped when $pagenow is customize.php.

Acceptance criteria

• CoBlocks loads without wp-edit-post dependency in Appearance > Customize block widgets editor.
• Post editor and Appearance > Widgets screens remain unaffected.

Checklist:

• My code is tested
• My code follows accessibility standards
• My code has proper inline documentation
• I've included any necessary tests
• I've included developer documentation
• I've added proper labels to this pull request