Add initial Go CLI skeleton

internal/protocol/json.go

@@ -0,0 +1,28 @@
+package protocol
+
+import (
+	"encoding/json"
+	"io"
+)
+
+type Success struct {
+	OK      bool           `json:"ok"`
+	Command string         `json:"command"`
+	Data    map[string]any `json:"data,omitempty"`
+}
+
+type Error struct {
+	OK    bool         `json:"ok"`
+	Error ErrorPayload `json:"error"`
+}
+
+type ErrorPayload struct {
+	Code    string `json:"code"`
+	Message string `json:"message"`
+}
+
+func WriteJSON(w io.Writer, v any) error {
+	enc := json.NewEncoder(w)
+	enc.SetIndent("", "  ")
+	return enc.Encode(v)
+}