Backport ToolsPanel SCSS Module migration to WordPress 7.1

[ciampo]

Backport of #80445 to WordPress 7.1.

What?

Backports the complete ToolsPanel migration from Emotion to an SCSS Module and the fix for the header heading typography regression.

Why?

The View migration exposed a stylesheet insertion-order conflict in ToolsPanel. The fix merged after the WordPress 7.1 branch split and needs to be applied to the beta branch separately.

How?

Cherry-picks the exact merged commit from #80445. The only manual conflict resolution creates a wp/7.1 Unreleased breaking-change section containing only the ToolsPanel entry and keeps the corresponding bug-fix entry in that release section.

Testing Instructions

Storybook

1. Open Components / ToolsPanel / Default.
2. Confirm the heading matches the After screenshot: compact inherited font size, emphasized weight, normal line height, and no extra margin.
3. Confirm the border, padding, two-column layout, and control spacing are unchanged.
4. Open the options menu, show or hide Scale, change values, and use Reset all.

Editor

1. Insert or select a Group block and open its Dimensions panel.
2. Confirm the corrected heading typography and expected control spacing.
3. Show or hide an optional control, change a value, and reset it.

Testing Instructions for Keyboard

Open the options menu with Enter or Space, navigate with the arrow keys, and dismiss it with Escape. Confirm focus remains visible and returns to the options button.

Screenshots or screencast

Emphasis on the heading regression, which is fixed by this backport.

Before	After

Use of AI Tools

Codex was used to prepare and verify the backport, resolve the release-branch changelog conflict, and draft this PR description.

[github-actions]

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Co-authored-by: ciampo <mciampini@git.wordpress.org>
Co-authored-by: aaronrobertshaw <aaronrobertshaw@git.wordpress.org>

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[github-actions]

Size Change: +928 B (+0.01%)

Total Size: 7.74 MB

📦 View Changed

Filename	Size	Change
build/scripts/components/index.min.js	272 kB	+928 B (+0.34%)

_{compressed-size-action}

[aaronrobertshaw]

Thanks for this @ciampo 👍

✅ Code changes match #80445
✅ ToolsPanel renders in Storybook as advertised in After screenshot
✅ Panel looks correct in block editor

LGTM 🚢