feat: add upload policies, daily limits, and storage quotas

- Add environment variables to configure anonymous uploads, daily upload caps, and default user storage limits.
- Update config loader to parse and validate the new settings.
- Implement backend logic to track daily usage and active storage per user.
- Update README and `.env.example` to document the new settings and admin panels.

backend/libs/handlers/dashboard.go

@@ -87,7 +87,7 @@ func (a *App) Dashboard(w http.ResponseWriter, r *http.Request) {
 		})
 	}
 
-	a.renderer.Render(w, http.StatusOK, "dashboard.html", web.PageData{
+	a.renderPage(w, r, http.StatusOK, "dashboard.html", web.PageData{
 		Title:       "My files",
 		Description: "Your Warpbox personal file space.",
 		CurrentUser: a.authService.PublicUser(user),