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/handlers/health.go

@@ -0,0 +1,20 @@
+package handlers
+
+import (
+	"net/http"
+	"time"
+
+	"warpbox.dev/backend/libs/helpers"
+)
+
+type healthResponse struct {
+	Status string `json:"status"`
+	Time   string `json:"time"`
+}
+
+func (a *App) Health(w http.ResponseWriter, r *http.Request) {
+	helpers.WriteJSON(w, http.StatusOK, healthResponse{
+		Status: "ok",
+		Time:   time.Now().UTC().Format(time.RFC3339),
+	})
+}