feat: atomic-wind CSS generator warmup

[abaicus]

Summary

• Adds Atomic Wind blocks style builder warmup when saving the editor content.

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Test instructions

• Logged in as Admin/Editor in wp-admin
• Page/post created with Atomic Wind blocks using visually obvious classes (e.g. bg-orange-500, md:py-36, columns)

Happy path — cache warms at save

• Open DevTools → Network; click Publish/Update
• A request fires to /?atomic_wind_css_warm=<nonce>&post_id=<id>&v=<timestamp> → 200, header X-Robots-Tag: noindex
• A follow-up POST to otter/v1/atomic-wind (style-builder saving the CSS)
• In DevTools → Elements, a hidden iframe #atomic-wind-css-warm-frame appears briefly, then is removed
• Post meta _atomic_wind_css is now populated and contains the expected classes — without visiting the front end
  • wp post meta get <post_id> _atomic_wind_css
• Front end (Incognito/fresh visitor) renders fully styled immediately — no flash of unstyled content

Re-save / updates

• Change a class (e.g. bg-orange-500 → bg-blue-500), Update
• _atomic_wind_css reflects the new class (the v=<timestamp> cache-bust forces a fresh render)
• Front end shows the updated styling after refresh

Edge cases

• No Atomic Wind blocks: plain post saves → no warm request fires, no errors
• Autosave: wait for autosave (don't manually save) → no warm pass triggered
• Failed save: simulate/observe a save failure → no warm pass triggered
• Rapid double-save: only one #atomic-wind-css-warm-frame exists at a time (old one removed)
• Timeout safety net: if the iframe never reports done, it's still removed after ~20s

Security gates

• Visiting /?atomic_wind_css_warm=bogus&post_id=<id> directly → not served (falls through to normal page)
• As Subscriber / logged-out with any nonce → warm page not served (requires edit_post)
• As post author/Admin with valid nonce → stripped warm document renders

Automated tests (optional, for devs)

• npm run test:unit:php:base -- --filter TestAtomicWindBlocks → green
• npm run lint -- src/atomic-wind and npm run lint:php → clean

Regression sanity

• Existing Atomic Wind pages still render correctly on front end
• No new console errors or PHP notices during save/view

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Checklist before the final review

• Included E2E or unit tests for the changes in this PR.
• Visual elements are not affected by independent changes.
• It is at least compatible with the minimum WordPress version.
• It loads additional script in frontend only if it is required.
• Does not impact the Core Web Vitals.
• In case of deprecation, old blocks are safely migrated.
• It is usable in Widgets and FSE.
• Copy/Paste is working if the attributes are modified.
• PR is following the best practices

[pirate-bot]

Bundle Size Diff

Package	Old Size	New Size	Diff
Animations	178.27 KB	178.27 KB	0 B (0.00%)
Blocks	1.52 MB	1.52 MB	0 B (0.00%)
CSS	7.87 KB	7.87 KB	0 B (0.00%)
Dashboard	111.06 KB	111.06 KB	0 B (0.00%)
Onboarding	68.14 KB	68.14 KB	0 B (0.00%)
Export Import	4.7 KB	4.7 KB	0 B (0.00%)
Pro	328.43 KB	328.43 KB	0 B (0.00%)

[pirate-bot]

Plugin build for 011e1e2 is ready 🛎️!

• Download Otter – Page Builder Blocks & Extensions for Gutenberg - Production ~ Development
• Download Otter Pro - Production ~ Development
• Download Blocks Animation - Production ~ Development
• Download Blocks CSS - Production ~ Development
• Download Blocks Export Import - Production ~ Development

[pirate-bot]

E2E Tests

Playwright Test Status: See serial and parallel matrix jobs

Performance Results

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