Improve the way errors are displayed in groups

### Description
QA identified that it could be helpful to highlight the group header/panel in addition to the individual fields that have validation issues. This would make it easier for users to quickly spot where problems exist, especially in larger forms.

### Design needs
Define how the panel header should be highlighted (e.g., red border, background, or icon).

Consider different states:

- If all fields in the group are invalid, should the entire header be red?
- If only one field is invalid, should the header still show an error state, or only the field itself?
- Ensure the design remains clear without overwhelming the user with too much red.

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### Checklist
- **Does it need UI/UX design?**
- [ ] Yes. Describe the UI/UX requirements or attach a Figma link in the "Design" section.
- [ ] No
- **Does it need API design?**
- [ ] Yes. Specify the endpoints, methods, or data structures needed.
- [ ] No
- **Does it need design around state flow?**
- [ ] Yes. Outline the state flow requirements.
- [ ] No
- **Does it need a test plan?**
- [ ] Yes. Add the test plan as a comment in this task or attach the document.
- [ ] No
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### User Stories

- **As a** [user type],
**I want** [functionality],
**so that** [benefit].

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### Design

- **Figma**: [Insert URL]
- **Design Docs**: [Insert URL]

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### Dependencies

-

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### Additional Notes

-

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### Related Issues

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No file, test, or entry point is named. Start by resolving the open questions about group and field error states and recording the agreed visual design; the issue currently does not define implementation locations or a concrete completion criterion.

Written by the indexing model from the issue text.