test(server): stop leaked fixtures from polluting later tests

TestMgmtAPI never closed its manager, so the notifier and task-archive workers started by New(context.Background()) kept claiming other tests digest batches and archive jobs. TestTaskOutcomeCard left a skill_usage miss row behind (the table has no foreign keys), which outranked TestSkillGapsReport fixture from the fourth -count iteration on.

server/mgmt_test.go

@@ -18,6 +18,10 @@ func TestMgmtAPI(t *testing.T) {
 	if m.pg == nil {
 		t.Skip("postgres unavailable — skipping management API test")
 	}
+	// New starts the notifier and task-archive workers on context.Background();
+	// closing the pool stops them from claiming later tests' digest batches
+	// and archive jobs.
+	defer m.Close()
 	td := t.TempDir()
 	s := New(context.Background(), m, td, td, td)
 	h := s.Handler()

server/task_outcome_test.go

@@ -23,6 +23,9 @@ func TestTaskOutcomeCard(t *testing.T) {
 	}
 	taskID, _ := strconv.ParseInt(task.ID, 10, 64)
 	defer func() { _ = m.pg.DeleteTask(taskID) }()
+	// skill_usage has no foreign keys, so DeleteTask leaves these rows behind,
+	// and their misses would outrank TestSkillGapsReport's fixture in later runs.
+	defer func() { _, _ = m.pg.Exec(`DELETE FROM skill_usage WHERE task_id=$1`, taskID) }()
 
 	if _, err := m.pg.Exec(`
 INSERT INTO findings(task_id,vulnclass,name,severity,status) VALUES