Fix datetime handling in energy charts

[MindFreeze]

Proposed change

Fix end datetime for energy charts. This was not visible on the other charts because they only show hourly data but the new power chart shows more detail.

Also changed the current state to only be added when viewing today. It wasn't a problem because it is just cut off when it's not in the selected period but this is cleaner.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• 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 Power Source Chart cut off at around 23:00 #28342
• This PR is related to issue or discussion:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• 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