Center energy dashboard bar charts on period midpoint

[MindFreeze]

Proposed change

Shift bar x-values to the period midpoint so bars visually span between the tick marks they represent. The solar forecast line is also shifted to align with the bars.

Fixes #30291

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After:

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

Additional information

• This PR fixes or closes issue: fixes alignment of bars in Energy Dashboard, Electricity usage. #30291
• This PR is related to issue or discussion:
• Link to documentation pull request:
• Link to developer documentation pull request:
• Link to backend pull request:

Checklist

• I understand the code I am submitting and can explain how it works.
• The code change is tested and works locally.
• There is no commented out code in this PR.
• I have followed the development checklist
• I have followed the perfect PR recommendations
• Any generated code has been carefully reviewed for correctness and compliance with project standards.

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

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

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