Reorganize directory structures

Signed-off-by: Sean Du <do4suki@gmail.com>

internal/model/webui.go

@@ -0,0 +1,8 @@
+package model
+
+// Msg ...
+type Msg struct {
+	Code     int    `json:"code"`
+	Message  string `json:"message"`
+	Redirect string `json:"redirect"`
+}