fix: 按 K-00 约定修复 Go SDK 断线重交与退避

sdk/go/client_test.go

@@ -95,8 +95,8 @@ func TestDedupReack(t *testing.T) {
 
 	msg, _ := marshalJSON(map[string]any{
 		"v": 1, "type": "msg", "id": "m1", "from": "a",
-		"to": map[string]any{"kind": "endpoint", "id": "ep1"},
-		"body": map[string]any{"enc": "utf8", "data": "hi"},
+		"to":         map[string]any{"kind": "endpoint", "id": "ep1"},
+		"body":       map[string]any{"enc": "utf8", "data": "hi"},
 		"send_at_ms": 1,
 	})
 	fake.InjectDown(msg)