fix(dev): address CLI review feedback

tools/homarr-dev/internal/docker/docker_test.go

@@ -25,3 +25,18 @@ func TestIsPortConflict(t *testing.T) {
 		t.Fatal("manifest error classified as port conflict")
 	}
 }
+
+func TestParseUsedDockerPortsPreservesLineBoundaries(t *testing.T) {
+	ports := parseUsedDockerPorts([]byte("6379/tcp\n0.0.0.0:7575->7575/tcp, [::]:7575->7575/tcp\n0.0.0.0:8000-8002->8000-8002/tcp\n"))
+	for _, port := range []int{7575, 8000, 8001, 8002} {
+		if !ports[port] {
+			t.Fatalf("port %d was not detected", port)
+		}
+	}
+}
+
+func TestFindFreePortRejectsOutOfRangeStart(t *testing.T) {
+	if port := FindFreePort(65536); port != 0 {
+		t.Fatalf("port = %d, want 0", port)
+	}
+}