fix(button): disable brightness styling when disabled

[rdlabo]

Summary

• apply --ion-color-*-brightness only to enabled solid submit buttons
• preserve Ionic's standard contrast color for disabled buttons
• add an enabled/disabled primary submit-button comparison to the component demo

Testing

• npm run build
• cd demo && npm test -- --configuration=ci
• cd demo && npm run lint
• cd demo && npm run build -- --configuration=production

Button screenshots are intentionally left to CI.

[github-actions]

Playwright test results

 2 failed
 88 passed

Details

 90 tests across 2 suites
 2 minutes, 9 seconds
 6cea43c
 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 button
chromium › screenshot.spec.ts › Screenshot Tests - Dark Mode › should match dark mode screenshot for button

[github-actions]

📊 Ionic 9 Playwright Test Report

View the detailed Ionic 9 report: https://rdlabo-dev.github.io/ionic-theme-ios26/pr-137/

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

[rdlabo]

/update-screenshots

[github-actions]

✅ Screenshots have been updated successfully!

The new screenshots have been committed to this PR.

[github-actions]

npm beta published

CI passed for the merge commit 8701a4e31f90. Install the immutable version with:

npm install @rdlabo/ionic-theme-ios26@9.1.0-beta.pr137.sha8701a4e31f90