feat: implement captive portal redirects for auto-loading the management page on hotspot mode (#2550)

src/network/CrossPointWebServer.cpp

@@ -353,6 +353,15 @@ void CrossPointWebServer::handleJszip() const {
 }
 
 void CrossPointWebServer::handleNotFound() const {
+  // in AP mode, redirect unmatched browser/captive-portal requests to "/" so the OS auto-opens the browser
+  // API requests (/api/*) still return 404 so XHR errors surface correctly
+  // see https://en.wikipedia.org/wiki/Captive_portal#Detection
+  if (apMode && !server->uri().startsWith("/api/")) {
+    server->sendHeader("Location", "/", true);
+    server->send(302, "text/plain", "");
+    return;
+  }
+
   String message = "404 Not Found\n\n";
   message += "URI: " + server->uri() + "\n";
   server->send(404, "text/plain", message);