feat: unify generated configuration loading and extensible decoders

examples/managedService/internal/config/loader.go

@@ -0,0 +1,7 @@
+package config
+
+import omniConfig "git.yuntuo.hk/k2safe/go-omni/config"
+
+// NewLoader is project-owned. JSON/YAML/XML work without changes. Register
+// additional format decoders here only when the project needs them.
+func NewLoader() (*omniConfig.Loader, error) { return omniConfig.NewLoader() }