fix: harden EPUB optimiser UI gating, size reporting, and picker teardown (#1947)

Co-authored-by: Justin Mitchell <justin@jmitch.com>

src/network/CrossPointWebServer.cpp

@@ -3,6 +3,7 @@
 #include <ArduinoJson.h>
 #include <Epub.h>
 #include <FsHelpers.h>
+#include <HalGPIO.h>
 #include <HalStorage.h>
 #include <Logging.h>
 #include <WiFi.h>
@@ -374,6 +375,7 @@ void CrossPointWebServer::handleStatus() const {
   doc["rssi"] = apMode ? 0 : WiFi.RSSI();
   doc["freeHeap"] = ESP.getFreeHeap();
   doc["uptime"] = millis() / 1000;
+  doc["device"] = gpio.deviceIsX3() ? "X3" : "X4";
 
   String json;
   serializeJson(doc, json);