Surfacing Cost Not Allocated

When an app's cost split references a department that no longer has users, that share was silently lost. Now it's visible so admins can act on it.

• New Cost not allocated section in the report shows each app's share, cost, Missing values, and Last seen date.
• Hover to Reconfigure opens the app's split directly for quick fixes.
• Also surfaced as a Not allocated row on each app's Cost allocation tab and in both CSV exports.