Column counts can become negative when switching views

[JoshuaJewell]

Problem

Column counts can become negative when switching views after changing selected columns.

This should never happen. A count should be recomputed from the active row set.

Current behaviour

1. Open a table in project, e.g. Run A
2. Click Hide counts
3. Open same table in different run, e.g. Run B
4. Actual: column count becomes negative.
5. Expected: column counts reflect the active row set.

Expected behaviour

• Column counts never render below zero.
• Switching views should not leave stale count state behind.
• Counts should be recomputed from the current active dataset/view/filter state.
• The UI should not derive displayed counts from fragile incremental subtraction across view changes.