fix: add alt attrs

[Soare-Robert-Daniel]

Closes #2619

Summary

Add missing image properties for EU law.

Screenshots

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Test instructions

Block	Slug	What to test	E2E	Manual
Icon List Item	themeisle-blocks/icon-list-item	Image icon → alt field. Frontend img always has alt (set or empty). Old post: no recovery → resave → alt=""	Yes: frontend, decorative, inspector, migration	ML prefill, clear alt via inspector
Icon List	themeisle-blocks/icon-list	Default library = Image → parent alt; new items inherit unless overridden	Yes: inheritance + override	Parent alt via Icons panel UI, ML prefill
Timeline Item	themeisle-blocks/timeline-item	Image icon → alt field. Frontend .o-timeline-icon img	Yes: frontend, decorative, inspector, migration	ML prefill
Image Slider	themeisle-blocks/slider	Per-slide alt in Images panel. No title on img. Old content: resave drops title	Yes: alt, no title, inspector, legacy resave	Reorder → alt stays with image
Flip Card	themeisle-blocks/flip	Front = Image → alt below preview	Yes: frontend	Inspector edit
Product Review	themeisle-blocks/review	Product image alt in inspector; check frontend (PHP)	—	Yes
Stripe Checkout	themeisle-blocks/stripe-checkout	Product img alt = product name. Needs Stripe + product image	—	Yes
About Author (deprecated)	themeisle-blocks/about-author	Avatar alt = author name	—	Yes
Posts Grid	themeisle-blocks/posts-grid	No change — smoke: featured img alt (ML → post title fallback)	—	Smoke only

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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	178.24 KB	178.24 KB	0 B (0.00%)
Blocks	1.5 MB	1.5 MB	4.83 KB (0.32%)
CSS	7.87 KB	7.87 KB	0 B (0.00%)
Dashboard	108.48 KB	108.48 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	320.08 KB	320.07 KB	-3 B (-0.00%)

[pirate-bot]

Plugin build for 0299fba 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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