feat: improve MD3 input supporting text layouts

[rdlabo]

Summary

• refine MD3 inset-list spacing for outlined ion-input and ion-textarea controls
• remove row dividers around outlined fields while preserving the Material outline appearance
• update the shared structured-list layout for input and textarea helper/error content
• hide empty supporting-text containers so they do not create unnecessary spacing
• add regular, helper, error, and outline variants to the inputs demo
• add unit coverage for the input and textarea variants

Verification

• npm run build
• cd demo && npm test -- --watch=false (34 tests passed)

[github-actions]

Playwright test results

 78 passed

Details

 78 tests across 1 suite
 1 minute, 32 seconds
 29479e2
 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.

[github-actions]

📊 Ionic 9 Playwright Test Report

View the detailed Ionic 9 report: https://rdlabo-dev.github.io/ionic-theme-md3/pr-29/

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

[rdlabo]

/update-screenshots

[github-actions]

❌ Failed to update screenshots.

Please check the workflow run for details.

[github-actions]

📊 Ionic 9 Playwright Test Report

View the detailed Ionic 9 report: https://rdlabo-dev.github.io/ionic-theme-md3/pr-29/

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-29/

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

[github-actions]

❌ Failed to update screenshots.

Please check the workflow run for details.

[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-29/

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

[github-actions]

❌ Failed to update screenshots.

Please check the workflow run for details.

[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-29/

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.

[github-actions]

📊 Ionic 9 Playwright Test Report

View the detailed Ionic 9 report: https://rdlabo-dev.github.io/ionic-theme-md3/pr-29/

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