fix: WordPress 7.0 admin UI compatibility

[imantsk]

Summary

WordPress 7.0 ships the "modern" admin redesign, which enlarges native form controls (40px vs 30/32px), reduces corner radius (2px vs 3/4px), recolours secondary buttons (transparent + modern-blue #3858E9) and changes link/icon metrics. Our admin UI was designed against the classic WP-6.9 control metrics + brand accent (#2271b1), so the redesign misaligned spacing, colours and icons across the Code Snippets screens.

This adds a small WP-admin compatibility layer that restores the classic control metrics on our admin pages only, plus targeted fixes for bespoke controls. Verified against three environments — local WP 7.0, local WP 6.9, and the remote WP 6.9 reference — with the remote as source of truth.

What's included

• feat: common/_wp-admin.scss compatibility layer (generic inputs/selects/buttons), imported into each admin bundle and ordered so it sits above WP core defaults but below the plugin's own per-control rules.
• fix: Go Pro menu button alignment + icon.
• fix: snippets list table — priority field, row-action links, status-filter (.subsubsub) and active-name colours.
• fix: Community Cloud "Pro Only" button keeps its brand-orange fill.
• fix: truncate-row-values class now reaches the list <table> (a ListTable prop-forwarding regression — the screen option did nothing on any WP version).
• fix: import drop-zone icon spacing.
• chore: row-action styling consolidated into the component partials (removes duplication with the compat layer).
• chore: hardcoded control colours/sizes extracted to theme variables.

Scoping / safety

• Compat bundles load only on Code Snippets pages; the two admin-wide files (menu, admin-bar) contain only CS-prefixed selectors. Verified other plugins (ACF, WPForms) + core screens keep their native WP 7.0 appearance.
• The compat layer overrides WP core but defers to the plugin's bespoke rules via source order, so no per-element exclusions are needed.

Verification

Computed-style + visual checks across edit-snippet, snippets list, settings, import and community-cloud on WP 6.9 / 7.0 / remote. No regression on WP 6.9. src/dist/ is CI-built (not committed).

[github-actions]

PHPUnit Test Failure

One or more PHP version targets failed in this workflow run.

See all PHPUnit errors (click to expand)

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Affected PHP version: 7.4, 8.0, 8.3, 8.4

PHPUnit\Framework\ExpectationFailedException
Code_Snippets\Tests\Cloud_API_Featured_Test::test_empty_filters_produce_same_cache_key
Empty filter values should hash identically to no filters.
Failed asserting that two strings are identical.
--- Expected
+++ Actual
@@ @@
-'cs_featured_snippets_v1781173252444.3_p1_pp10_d751713988987e9331980363e24189ce'
+'cs_featured_snippets_v1781173252444.2_p1_pp10_d751713988987e9331980363e24189ce'

/home/runner/work/code-snippets/code-snippets/tests/phpunit/test-cloud-api-featured.php:383
phpvfscomposer:///home/runner/work/code-snippets/code-snippets/src/vendor/phpunit/phpunit/phpunit:106

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Please review the failing jobs and fix the issues before merging.