Add HAFloatingActionButton component

[hdcodedev]

Summary

As part of the Shortcuts V2 work we're building, we added a reusable HAFloatingActionButton component so it can be shared across features.

Checklist

• New or updated tests have been added to cover the changes following the testing guidelines.
• The code follows the project's code style and best_practices.
• The changes have been thoroughly tested, and edge cases have been considered.
• Changes are backward compatible whenever feasible. Any breaking changes are documented in the changelog for users and/or in the code for developers depending on the relevance.

Screenshots

Link to pull request in documentation repositories

User Documentation: home-assistant/companion.home-assistant#

Developer Documentation: home-assistant/developers.home-assistant#

Any other notes

[Copilot]

Pull request overview

This PR introduces a reusable HAFloatingActionButton Compose component in :common so features (e.g., Shortcuts V2) can share a Home Assistant–themed FAB implementation and validate its visuals via screenshot tests.

Changes:

• Added HAFloatingActionButton component with ButtonVariant-driven color theming via LocalHAColorScheme.
• Added a light/dark screenshot test that renders the FAB across all ButtonVariant values.
• Included a preview for quick local inspection of the component.

Reviewed changes

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

File	Description
common/src/main/kotlin/io/homeassistant/companion/android/common/compose/composable/HAFloatingActionButton.kt	Adds the new HA-themed FAB composable + preview.
common/src/screenshotTest/kotlin/io/homeassistant/companion/android/compose/composable/HAFloatingActionButtonScreenshotTest.kt	Adds screenshot coverage for the FAB across variants in light/dark.

[TimoPtr]

Small changes and we are ready to go. As for UI feedback for now we don't have, so let's go with the default and use the custom component so that we can change everywhere in one shot when needed.

[TimoPtr]

I wonder if you should actually use the contentColor there? no or M3 is already handling this properly

[hdcodedev]

It is needed because we are using variants. If we want this one to be primary only, then we could probably drop the explicit colors.

[TimoPtr]

The imageVector is tint with the contentColor?

[home-assistant]

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks 👍

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