Gallery: Improve mobile lightbox with animated swiping

[jasmussen]

What?

Followup to #62906. Adds animation to the swiping gesture for mobile galleries:

Why?

When you have a gallery set to lightbox ("expand on click"), no mobile you can open it and use a swipe gesture to advance between images. However there is no visual feedgback that this is possible. This PR adds that.

Testing Instructions

Create a gallery, set to expand on click, then test on mobile, or using the web-inspector set to device emulation. Test swiping images to advance.

Use of AI Tools

Claude Opus 4.7.

[github-actions]

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[github-actions]

Size Change: +1.32 kB (+0.02%)

Total Size: 7.76 MB

📦 View Changed

Filename	Size	Change
build/modules/block-library/image/view.min.js	3.08 kB	+432 B (+16.34%)	⚠️
build/styles/block-library/image/style-rtl.css	3.07 kB	+119 B (+4.03%)
build/styles/block-library/image/style-rtl.min.css	1.97 kB	+104 B (+5.57%)	🔍
build/styles/block-library/image/style.css	3.08 kB	+121 B (+4.09%)
build/styles/block-library/image/style.min.css	1.97 kB	+106 B (+5.7%)	🔍
build/styles/block-library/style-rtl.css	22.5 kB	+111 B (+0.5%)
build/styles/block-library/style-rtl.min.css	19 kB	+107 B (+0.57%)
build/styles/block-library/style.css	22.7 kB	+116 B (+0.51%)
build/styles/block-library/style.min.css	19 kB	+103 B (+0.55%)

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[jasmussen]

Rebased, and worked in some small improvements.

[github-actions]

Flaky tests detected in 022d8e4.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/30269701069
📝 Reported issues:

• [Flaky Test] should cut and paste individual blocks with collapsed selection #80248 in /test/e2e/specs/editor/various/copy-cut-paste.spec.js

[fcoveram]

It works well for me. It would be nicer if, after a certain number of pixels of swiping, the next/prev image is revealed to make the transition smoother and reinforce the swipe direction. Right now, the new image shows up slightly abruptly.

[jasmussen]

Right now, the new image shows up slightly abruptly.

I agree. When I worked on that, this aspect was a bit of a larger undertaking, so in the hopes of making this a small iterative improvement, I chose this simpler approach. But it should be possible to upgrade it with a second PR. Curious if we can get a developer instinct on this, happy either way.