Optional dividers between rows and columns in the views list components

Problem/Motivation

Stacked card lists and three-across card rows in the design have a line between items. When those lists come from a view, the views components have no way to draw it.

Proposed resolution

• views-view-unformatted: new row_divider and row_divider_color props draw the divider atom between rows.
• views-view-grid: new column_divider prop draws a vertical line between columns from md up, like the section component.

Both default to off, so existing listings do not change. Neither component is a Canvas component, so no component version changes.

Remaining tasks

• ✅ File an issue
• ❌ Addition/Change/Update/Fix
• ❌ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ➖ Developer Documentation support
• ➖ User Guide Documentation support
• ➖ UX/UI designer responsibilities
• ➖ Accessibility and Readability
• ❌ Reviewed by a human
• ❌ Code review by maintainers
• ❌ Full testing and approval
• ❌ Credit contributors
• ❌ Review with the product owner
• ❌ Update Release Notes
• ❌ Release

User interface changes

• N/A

API changes

• Three new optional props on two views components.

Data model changes

• N/A

Release notes snippet

• Views lists can draw dividers between rows and columns.

AI-Generated: Yes. Drafted and tested with Claude Code, reviewed by the contributor.