fix(web): break metricsEqual lastSeen dep-loop; add staleTime to test

Remove lastSeen from metricsEqual in ServerWorkspaceRows: computeFleetAggregates
never reads lastSeen, so comparing it in metricsEqual causes background TanStack
Query refetches (dataUpdatedAt changes) to trigger spurious onMetrics callbacks,
cascading into a Dashboard → ServerWorkspaceRows render loop that hits React's
100-render limit in CI.

Add staleTime: Infinity to the test QueryClient to prevent background refetches
from interfering with test assertions.

packages/web/src/components/dashboard/ServerWorkspaceRows.tsx

@@ -34,7 +34,6 @@ function metricsEqual(a: FleetRowMetrics, b: FleetRowMetrics): boolean {
 		a.conclusionCount === b.conclusionCount &&
 		a.queueActive === b.queueActive &&
 		a.queuePending === b.queuePending &&
-		a.lastSeen === b.lastSeen &&
 		a.health === b.health
 	);
 }