Show Responsive viewport/state indicator in save confirmation dialog

[shail-mehta]

What?

Closes #80836

This PR updates the save confirmation modal to indicate which responsive state (e.g. Mobile, Tablet) a style change was made in, when the change comes from a responsive style variation set via Editor > Styles > Blocks > Title.

Why?

When a user edits block styles for a specific viewport (e.g. Mobile only), the save confirmation screen only shows the block style was changed - not which viewport it applies to. This ambiguity can lead users to think the change is global, risking unintended publishes. Making the viewport explicit improves clarity and confidence before saving.

How?

Surface the active viewport/state (Mobile/Tablet/Default) tied to a style edit in the change-tracking data used by the save panel, and append a viewport indicator to affected entries.

Testing Instructions

• Go to Editor > Styles > Blocks > Title
• Select the State from the drop-down
• Make a color or Font change
• Hit the save button to read the confirmation screen

Screenshots

Single Block Style Update	Multiple Block Style Update

Use of AI Tools

• Yes

[github-actions]

Size Change: +1.62 kB (+0.02%)

Total Size: 7.78 MB

📦 View Changed

Filename	Size	Change
build/scripts/core-data/index.min.js	37.1 kB	+590 B (+1.61%)
build/scripts/editor/index.min.js	502 kB	+619 B (+0.12%)
build/styles/core-data/style-rtl.css	885 B	+107 B (+13.75%)	⚠️
build/styles/core-data/style-rtl.min.css	465 B	+97 B (+26.36%)	🚨
build/styles/core-data/style.css	884 B	+107 B (+13.77%)	⚠️
build/styles/core-data/style.min.css	464 B	+97 B (+26.43%)	🚨

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[github-actions]

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Co-authored-by: shail-mehta <shailu25@git.wordpress.org>
Co-authored-by: bph <bph@git.wordpress.org>

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[github-actions]

Flaky tests detected in 9a3002d.
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/30708342985
📝 Reported issues:

• [Flaky Test] Post editor proper template resolution #77280 in /test/e2e/specs/editor/various/template-resolution.spec.js