Adds new integration [jrmattila/ha-elenia]

[jrmattila]

Checklist

• I've read the publishing documentation.
• I've added the HACS action to my repository.
• (For integrations only) I've added the hassfest action to my repository.
• The actions are passing without any disabled checks in my repository.
• I've added a link to the action run on my repository below in the links section.
• I've created a new release of the repository after the validation actions were run successfully.

Links

Link to current release: https://github.com/jrmattila/ha-elenia/releases/tag/1.0.0
Link to successful HACS action (without the ignore key): https://github.com/jrmattila/ha-elenia/actions/runs/11709012808
Link to successful hassfest action (if integration): https://github.com/jrmattila/ha-elenia/actions/runs/11709012790