Skip live network feed test under -short for deterministic make check (closes #2)

TestRouteWatchLiveFeed streams the live RIPE RIS feed for about five
seconds, which made make check nondeterministic and network-dependent.
Guard it with a testing.Short() skip and pass -short in both go test
lines of script/test, so the default suite runs offline and
deterministically. The README documents how to run the live test on
demand.

Test-only change; no production behavior changes.

Model: opus-4-8

internal/routewatch/app_integration_test.go

@@ -426,6 +426,9 @@ func (m *mockStore) Ping(ctx context.Context) error {
 }
 
 func TestRouteWatchLiveFeed(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping live RIPE RIS network feed test in short mode; run without -short to include it")
+	}
 
 	// Create mock database
 	mockDB := newMockStore()