feat: initialize warpbox.dev project structure and backend

Initialize the repository with the core Go backend architecture and a frontend mockup for warpbox.dev, a self-hosted file-sharing application.

- Set up Go backend modules for configuration, HTTP server, middleware, handlers, and templates.
- Add local development scripts, environment templates, and basic project configuration.
- Include a React-based frontend mockup under the docs directory.

backend/libs/middleware/chain.go

@@ -0,0 +1,12 @@
+package middleware
+
+import "net/http"
+
+type Middleware func(http.Handler) http.Handler
+
+func Chain(handler http.Handler, middleware ...Middleware) http.Handler {
+	for i := len(middleware) - 1; i >= 0; i-- {
+		handler = middleware[i](handler)
+	}
+	return handler
+}