init: hgmj server initial commit

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

common/conf/conf.go

@@ -0,0 +1,23 @@
+package conf
+
+import (
+	"encoding/json"
+	"io"
+	"os"
+)
+
+func LoadJSON(path string, cfg interface{}) error {
+	f, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer func() { _ = f.Close() }()
+	bs, err := io.ReadAll(f)
+	if err != nil {
+		return err
+	}
+	if err = json.Unmarshal(bs, cfg); err != nil {
+		return err
+	}
+	return nil
+}