fix 3.5 touch freeze: async WiFi scan and GT911 reset.

Scan no longer blocks LVGL; always hw-reset GT911; larger buttons and click areas.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/wifi_prov.cpp

@@ -26,6 +26,7 @@ static DNSServer *g_dns = nullptr;
 static WebServer *g_http = nullptr;
 static bool g_portal = false;
 static char g_ap_ssid[33] = WIFI_PROV_AP_SSID;
+static bool g_scan_async = false;
 
 static void set_state(WifiProvState s) {
   if (g_state == s) {
@@ -269,27 +270,11 @@ void wifi_prov_connect_to(const char *ssid, const char *password) {
   begin_sta_connect(g_ssid, g_pass);
 }
 
-int wifi_prov_scan(WifiScanItem *out, int max_items) {
-  if (!out || max_items <= 0) {
-    return 0;
-  }
-  if (max_items > WIFI_PROV_MAX_SCAN) {
-    max_items = WIFI_PROV_MAX_SCAN;
-  }
-
-  // SoftAP 时用 APSTA，否则扫描会关掉 AP
-  if (g_portal) {
-    WiFi.mode(WIFI_AP_STA);
-  } else {
-    WiFi.mode(WIFI_STA);
-  }
-
-  const int found = WiFi.scanNetworks(/*async=*/false, /*hidden=*/true);
+static int fill_scan_results(WifiScanItem *out, int max_items, int found) {
   if (found <= 0) {
     WiFi.scanDelete();
     return 0;
   }
-
   const int n = found < max_items ? found : max_items;
   for (int i = 0; i < n; ++i) {
     String s = WiFi.SSID(i);
@@ -302,6 +287,76 @@ int wifi_prov_scan(WifiScanItem *out, int max_items) {
   return n;
 }
 
+int wifi_prov_scan(WifiScanItem *out, int max_items) {
+  if (!out || max_items <= 0) {
+    return 0;
+  }
+  if (max_items > WIFI_PROV_MAX_SCAN) {
+    max_items = WIFI_PROV_MAX_SCAN;
+  }
+  if (g_scan_async) {
+    WiFi.scanDelete();
+    g_scan_async = false;
+  }
+
+  if (g_portal) {
+    WiFi.mode(WIFI_AP_STA);
+  } else {
+    WiFi.mode(WIFI_STA);
+  }
+
+  const int found = WiFi.scanNetworks(/*async=*/false, /*hidden=*/true);
+  return fill_scan_results(out, max_items, found);
+}
+
+bool wifi_prov_scan_start() {
+  if (g_scan_async) {
+    return true;
+  }
+  if (g_portal) {
+    WiFi.mode(WIFI_AP_STA);
+  } else {
+    WiFi.mode(WIFI_STA);
+  }
+  /* async — does not block LVGL loop */
+  const int16_t rc = WiFi.scanNetworks(/*async=*/true, /*hidden=*/true);
+  if (rc == WIFI_SCAN_FAILED) {
+    Serial.println("[wifi] scan start failed");
+    return false;
+  }
+  g_scan_async = true;
+  Serial.println("[wifi] scan async started");
+  return true;
+}
+
+bool wifi_prov_scan_busy() { return g_scan_async; }
+
+int wifi_prov_scan_poll(WifiScanItem *out, int max_items) {
+  if (!g_scan_async) {
+    return 0;
+  }
+  if (!out || max_items <= 0) {
+    return 0;
+  }
+  if (max_items > WIFI_PROV_MAX_SCAN) {
+    max_items = WIFI_PROV_MAX_SCAN;
+  }
+
+  const int16_t found = WiFi.scanComplete();
+  if (found == WIFI_SCAN_RUNNING) {
+    return -1;
+  }
+  g_scan_async = false;
+  if (found == WIFI_SCAN_FAILED) {
+    WiFi.scanDelete();
+    Serial.println("[wifi] scan failed");
+    return 0;
+  }
+  const int n = fill_scan_results(out, max_items, found);
+  Serial.printf("[wifi] scan done n=%d\n", n);
+  return n;
+}
+
 void wifi_prov_portal_start(const char *ap_ssid) {
   if (g_portal) {
     return;