Add documentation for progress bar customization on Android

[inukiwi]

Proposed change

This feature adds support for progress bar customization on Android 16.0+ devices, as shown here.
Screenshot of an example notification:

Type of change

• Document existing features within Home Assistant Companion App
• Document new or changing features for which there is an existing pull request elsewhere
• Spelling or grammatical corrections, or rewording for improved clarity
• Changes to the backend of this documentation
• Remove stale or deprecated documentation

Checklist

• I have read and followed the documentation guidelines.
• I have verified that my changes render correctly in the documentation.

Additional information

• Link to relevant existing code or pull request: Progress bar customization android#6527

[Copilot]

Pull request overview

Adds documentation to the Companion Apps docs describing the new Android 16.0+ “progress-centric” notification progress bar customization options, including an example and screenshot.

Changes:

• Document progress bar styling options (segments, points, and icons/colors) for Android 16.0+ notifications.
• Add a YAML automation example demonstrating the new parameters.
• Add a screenshot asset illustrating the customized progress bar result.

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated 4 comments.

File	Description
docs/notifications/basic.md	Adds a new “Styling the progress bar” section with supported parameters, caveats, and an example.
static/assets/android/progress_bar_customized.png	Adds the screenshot referenced by the new documentation section.

[inukiwi]

Feedback has been implemented

[c0ffeeca7]

Nice! LGTM.

[c0ffeeca7]

a merge conflict has appeared