fix: apply inset styles to all list groups

[rdlabo]

Summary

• share the supported structured-list group selector list from the utility module
• apply MD3 inset item styles to item, reorder, accordion, and radio groups
• use descendant selectors so wrapped ion-item components remain supported
• derive radio helper/error text padding from the layout's outer inset

The outer inset resolves to 8px for MD3 instead of being omitted.

Verification

• npm run build
• Prettier check for the changed SCSS files
• git diff --check
• inspected generated CSS for all four group selectors and the 8px radio support-text inset
• confirmed structured-list.scss is byte-identical with ionic-theme-ios26

[github-actions]

Playwright test results

 4 failed
 74 passed

Details

 78 tests across 1 suite
 1 minute, 59 seconds
 3bc1ef7
 This detailed result covers Ionic 9 only. Ionic 8 runs against the same screenshots in a separate matrix job; check the workflow run for both results. To update the screenshots, comment with /update-screenshots.

Failed tests

chromium › screenshot.spec.ts › Screenshot Tests - All Routes › should match screenshot for radio
chromium › screenshot.spec.ts › Screenshot Tests - All Routes › should match screenshot for reorder
chromium › screenshot.spec.ts › Screenshot Tests - Dark Mode › should match dark mode screenshot for radio
chromium › screenshot.spec.ts › Screenshot Tests - Dark Mode › should match dark mode screenshot for reorder

[github-actions]

📊 Ionic 9 Playwright Test Report

View the detailed Ionic 9 report: https://rdlabo-dev.github.io/ionic-theme-md3/pr-33/

Ionic 8 runs against the same screenshots in a separate matrix job. View both results in the workflow run.

[github-actions]

📊 Ionic 9 Playwright Test Report

View the detailed Ionic 9 report: https://rdlabo-dev.github.io/ionic-theme-md3/pr-33/

Ionic 8 runs against the same screenshots in a separate matrix job. View both results in the workflow run.

[github-actions]

📊 Ionic 9 Playwright Test Report

View the detailed Ionic 9 report: https://rdlabo-dev.github.io/ionic-theme-md3/pr-33/

Ionic 8 runs against the same screenshots in a separate matrix job. View both results in the workflow run.

[github-actions]

📊 Ionic 9 Playwright Test Report

View the detailed Ionic 9 report: https://rdlabo-dev.github.io/ionic-theme-md3/pr-33/

Ionic 8 runs against the same screenshots in a separate matrix job. View both results in the workflow run.

[github-actions]

📊 Ionic 9 Playwright Test Report

View the detailed Ionic 9 report: https://rdlabo-dev.github.io/ionic-theme-md3/pr-33/

Ionic 8 runs against the same screenshots in a separate matrix job. View both results in the workflow run.

[rdlabo]

/update-screenshots

[github-actions]

📊 Ionic 9 Playwright Test Report

View the detailed Ionic 9 report: https://rdlabo-dev.github.io/ionic-theme-md3/pr-33/

Ionic 8 runs against the same screenshots in a separate matrix job. View both results in the workflow run.

[github-actions]

✅ Screenshots have been updated successfully!

The new screenshots have been committed to this PR.