Add long_running, real_network, test_project, and failing columns to
dotnet_tests table. Set test_project for all 3,491 rows. Mark 9 known
failing tests. Fix slopwatch hook to use absolute path.
Reconcile close reason tracking: feature branch's MarkClosed() and
ShouldSkipFlush/FlushAndCloseAsync now use main's ClientClosedReason
enum. ClosedState enum retained for forward compatibility.