New UI (#157, #164)

- Add a react UI to replace the plain HTML one. 
- Serve as a foundation for better GUI interactions

proxy/ui_embed.go

@@ -0,0 +1,24 @@
+package proxy
+
+import (
+	"embed"
+	"io/fs"
+	"net/http"
+)
+
+//go:embed ui_dist
+var reactStaticFS embed.FS
+
+// GetReactFS returns the embedded React filesystem
+func GetReactFS() (http.FileSystem, error) {
+	subFS, err := fs.Sub(reactStaticFS, "ui_dist")
+	if err != nil {
+		return nil, err
+	}
+	return http.FS(subFS), nil
+}
+
+// GetReactIndexHTML returns the main index.html for the React app
+func GetReactIndexHTML() ([]byte, error) {
+	return reactStaticFS.ReadFile("ui_dist/index.html")
+}