feat(security): add trusted proxies and abuse event cleanup

- Add `WARPBOX_TRUSTED_PROXIES` configuration to restrict accepted forwarded client IP headers to specific proxy IPs/CIDRs, securing client IP resolution.
- Integrate `BanService` into the background cleanup job to automatically purge expired abuse and ban evidence events.
- Update documentation with reverse proxy security guidelines and a production systemd deployment guide.

backend/libs/handlers/manage.go

@@ -31,6 +31,7 @@ func (a *App) ManageBox(w http.ResponseWriter, r *http.Request) {
 		Description: "Delete this anonymous Warpbox upload.",
 		Data:        a.managePageData(box, r.PathValue("token")),
 	})
+	a.logger.Info("anonymous manage page viewed", "source", "anonymous-delete", "severity", "user_activity", "code", 2102, "box_id", box.ID, "ip", uploadClientIP(r))
 }
 
 func (a *App) ManageDeleteBox(w http.ResponseWriter, r *http.Request) {
@@ -40,10 +41,11 @@ func (a *App) ManageDeleteBox(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if err := a.uploadService.DeleteBoxWithToken(box.ID, r.PathValue("token")); err != nil {
-		a.logger.Warn("anonymous delete failed", "source", "anonymous-delete", "severity", "warn", "code", 4102, "box_id", box.ID, "error", err.Error())
+		a.logger.Warn("anonymous delete failed", "source", "anonymous-delete", "severity", "warn", "code", 4102, "box_id", box.ID, "ip", uploadClientIP(r), "error", err.Error())
 		http.NotFound(w, r)
 		return
 	}
+	a.logger.Info("anonymous box deleted", "source", "anonymous-delete", "severity", "user_activity", "code", 2103, "box_id", box.ID, "ip", uploadClientIP(r))
 	http.Redirect(w, r, "/d/"+box.ID+"/deleted", http.StatusSeeOther)
 }
 
@@ -58,10 +60,12 @@ func (a *App) ManageDeleted(w http.ResponseWriter, r *http.Request) {
 func (a *App) loadManagedBox(w http.ResponseWriter, r *http.Request) (services.Box, bool) {
 	box, err := a.uploadService.GetBox(r.PathValue("boxID"))
 	if err != nil {
+		a.logger.Warn("anonymous manage missing box", "source", "anonymous-delete", "severity", "warn", "code", 4103, "box_id", r.PathValue("boxID"), "ip", uploadClientIP(r))
 		http.NotFound(w, r)
 		return services.Box{}, false
 	}
 	if !a.uploadService.VerifyDeleteToken(box, r.PathValue("token")) {
+		a.logger.Warn("anonymous manage invalid token", "source", "anonymous-delete", "severity", "warn", "code", 4104, "box_id", box.ID, "ip", uploadClientIP(r))
 		http.NotFound(w, r)
 		return services.Box{}, false
 	}