test: add portal hardware lifecycle coverage

lib/WiFiManager/include/WiFiManager.h

@@ -1012,6 +1012,10 @@ protected:
     void          failAsyncScan(wm_scan_state_t state, int scanResult = WIFI_SCAN_FAILED);
     void          resetAsyncScan(bool clearResults);
     void          invalidateScanResults();
+    // Release cached scan-result vector capacity after a portal fully closes.
+    // Do not use this during normal refreshes: the cache is intentionally kept
+    // while the portal is active so the UI can render nearby networks.
+    void          releaseScanResultStorage();
     bool          hasFreshScanResults(unsigned int cachetime) const;
     bool          canRunAsyncScan() const;
     void          cacheScanResults(int networksFound);

lib/WiFiManager/src/WiFiManager.cpp

@@ -1373,6 +1373,7 @@ bool WiFiManager::shutdownConfigPortal(){
   }
 
   resetAsyncScan(true);
+  releaseScanResultStorage();
 
   if(!configPortalActive) return false;
 
@@ -1954,6 +1955,15 @@ void WiFiManager::resetAsyncScan(bool clearResults) {
     _scan.visibleNetworkCount = _numNetworks;
   }
 }
+void WiFiManager::releaseScanResultStorage() {
+  // clear() releases String payloads but deliberately retains the vector's
+  // backing allocation. At portal shutdown that cache has no remaining value,
+  // so release it with the server/DNS objects rather than carrying it into the
+  // normal connected runtime. Keep this out of the refresh path to avoid
+  // needless allocation churn while a user is looking at nearby networks.
+  std::vector<WiFiScanNetwork>().swap(_scanResultsCache);
+}
+
 
 void WiFiManager::invalidateScanResults() {
   _scan.resultsValid = false;

lib/WiFiManager/src/WiFiManagerHandlers.cpp

@@ -16,10 +16,6 @@
 #include <cstring>
 #if defined(ESP8266) || defined(ESP32)
 
-#ifndef WM_PAGE_RESERVE_BYTES
-#define WM_PAGE_RESERVE_BYTES 8192
-#endif
-
 static void jsonAppendEscaped(String& out, const String& s) {
   for (size_t i = 0; i < s.length(); i++) {
     const char c = s[i];
@@ -56,7 +52,7 @@ namespace {
 
 const char kEmptyPortalPlaceholder[] PROGMEM = "";
 
-inline void reservePage(String& page, size_t extraBytes = WM_PAGE_RESERVE_BYTES) {
+inline void reservePage(String& page, size_t extraBytes) {
   if (extraBytes == 0) return;
   const size_t targetLen = page.length() + extraBytes;
   (void)page.reserve(targetLen);
@@ -259,21 +255,23 @@ void WiFiManagerHandlers::collectVisibleScanResults(std::vector<const WiFiManage
   }
 
   if (_wm->_removeDuplicateAPs) {
-    std::vector<const WiFiManager::WiFiScanNetwork*> deduped;
-    deduped.reserve(networks.size());
+    // Reuse the pointer storage that was already reserved above. Building a
+    // second vector briefly doubles this request's scan-list allocation on
+    // constrained ESP8266 heaps.
+    size_t kept = 0;
     for (const auto* network : networks) {
       bool duplicate = false;
-      for (const auto* existing : deduped) {
-        if (existing->ssid == network->ssid) {
+      for (size_t i = 0; i < kept; ++i) {
+        if (networks[i]->ssid == network->ssid) {
           duplicate = true;
           break;
         }
       }
       if (!duplicate) {
-        deduped.push_back(network);
+        networks[kept++] = network;
       }
     }
-    networks.swap(deduped);
+    networks.resize(kept);
   }
 }