Read-only diagram versions allow field deletion from canvas

[Jadu07]

Describe the bug

When viewing an older read-only version of a diagram, the minus button beside a table field on the canvas still removes the field. The deletion happens immediately even though the layout is read-only.

To Reproduce

1. Open a diagram version in read-only mode.
2. On the canvas, hover a table row to reveal the minus icon.
3. Click the minus icon.
4. Observe that the field disappears despite the read-only state.

Expected behavior
In read-only mode, field deletions should be blocked, the minus button should be disabled and no changes should occur.

Desktop (please complete the following information):

• OS: macOS
• Browser: Chrome