feat(rtl): nodebridge decodes JS arrays/objects to native PRG values

jsValToValue now recursively converts JS arrays/objects (the "json" wire
type) into native hbrt arrays/hashes, so PRG can Len()/index/hb_HGetDef the
results of npm methods (e.g. os.cpus()[1]:model). Strings/numbers/booleans/
buffers unchanged.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

hbrtl_ext/nodebridge/nodebridge.go

@@ -370,7 +370,13 @@ func jsValToValue(val map[string]interface{}) hbrt.Value {
 	t := str(val["t"])
 	v := str(val["v"])
 	switch t {
-	case "string", "buffer", "json":
+	case "string", "buffer":
+		return hbrt.MakeString(v)
+	case "json": // JS array/object → 네이티브 PRG 배열/해시로 디코드
+		var parsed interface{}
+		if err := json.Unmarshal([]byte(v), &parsed); err == nil {
+			return jsonToValue(parsed)
+		}
 		return hbrt.MakeString(v)
 	case "number":
 		if f, err := strconv.ParseFloat(v, 64); err == nil {
@@ -384,6 +390,34 @@ func jsValToValue(val map[string]interface{}) hbrt.Value {
 	}
 }
 
+// jsonToValue: 디코드된 JSON 값을 네이티브 hbrt.Value(배열/해시/스칼라)로.
+func jsonToValue(x interface{}) hbrt.Value {
+	switch v := x.(type) {
+	case nil:
+		return hbrt.MakeNil()
+	case bool:
+		return hbrt.MakeBool(v)
+	case float64:
+		return hbrt.MakeDoubleAuto(v)
+	case string:
+		return hbrt.MakeString(v)
+	case []interface{}:
+		items := make([]hbrt.Value, len(v))
+		for i, e := range v {
+			items[i] = jsonToValue(e)
+		}
+		return hbrt.MakeArrayFrom(items)
+	case map[string]interface{}:
+		pairs := make([]hbrt.Value, 0, len(v)*2)
+		for k, e := range v {
+			pairs = append(pairs, hbrt.MakeString(k), jsonToValue(e))
+		}
+		return hbrt.MakeHashFrom(hbrt.HashFromPairs(pairs))
+	default:
+		return hbrt.MakeNil()
+	}
+}
+
 func str(v interface{}) string {
 	if s, ok := v.(string); ok {
 		return s