Test a future time 90 seconds ahead in TestRelativeTime

An hour ahead comes out as 0s even without the clamp to zero, so the
case did not pin it. 90 seconds ahead would come out as -30s.

Model: opus-5-5

internal/handlers/webhook_stats_test.go

@@ -604,7 +604,7 @@ func TestRelativeTime(t *testing.T) {
 		{90000 * time.Second, "1d1h"},
 		{400*24*time.Hour + 3*time.Hour, "400d3h"},
 		// An event time ahead of the server clock.
-		{-time.Hour, "0s"},
+		{-90 * time.Second, "0s"},
 	}
 
 	for _, tt := range tests {