Area Card Editor: show a list of relevant entities

[karwosts]

Proposed change

Display the list of entities used in the area card editor. Otherwise this information is quite difficult to find, and often cause unexpected result when there is an extra entity that user doesn't realize.

Perhaps as a further enhancement, the bullet-list could have added checkboxes, which can allow for deselecting/ignoring certain entities from the card.

Also this PR unifies the code for filtering entities in the area between area-card and area-card-editor. Previously they were both implementing the solution in different ways.

Type of change

• [ ] Dependency upgrade
• [ ] Bugfix (non-breaking change which fixes an issue)
• [x] New feature (thank you!)
• [ ] Breaking change (fix/feature causing existing functionality to break)
• [ ] Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue or discussion:
• Link to documentation pull request:

Checklist

• [x] The code change is tested and works locally.
• [x] There is no commented out code in this PR.
• [ ] Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• [ ] Documentation added/updated for www.home-assistant.io

Summary by CodeRabbit

• New Features

  • Enhanced "Area" card to display observed and controlled entities in the UI.

• Refactor

  • Refactored internal functions to public exports for better external access to domain-specific entity retrieval and filtering.
  • Improved data management and UI logic with new subscription methods for device and entity registries.

• Localization

  • Added new translations for "observed_entities" and "controlled_entities" in the "Area" card.