fix 2025.12 deprecation of config flow entries

[sfstar]

Breaking change

Proposed change

Address breaking changes in upcoming homeassistant core config flows

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• 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 Deprecated usage of config_entry in option flow (will break in Home Assistant 2025.12) #392
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• The code has been formatted using Ruff (ruff format custom_components/victron)