apply go-centric architecture optimizations and document them in readme

pkg/runtimecfg/snapshot.go

@@ -0,0 +1,25 @@
+package runtimecfg
+
+import (
+	"sync/atomic"
+
+	"clawgo/pkg/config"
+)
+
+var current atomic.Value // *config.Config
+
+func Set(cfg *config.Config) {
+	if cfg == nil {
+		return
+	}
+	current.Store(cfg)
+}
+
+func Get() *config.Config {
+	v := current.Load()
+	if v == nil {
+		return nil
+	}
+	cfg, _ := v.(*config.Config)
+	return cfg
+}