Implement comprehensive test suite improvements

- Added 42 new tests covering critical functionality:
  * WiFi connection flow tests (6 tests)
  * Callback firing verification tests (4 tests)
  * DNS server lifecycle tests (3 tests)
  * Error condition tests (7 tests)
  * Parameter value management tests (5 tests)
  * WiFi scanning tests (4 tests)
  * State transition tests (4 tests)
  * Integration tests (5 tests)
  * Stress tests (5 tests)

- Fixed compilation errors by replacing protected connectWifi() calls with public autoConnect()
- Fixed config reset callback test to use resetSettings() instead of erase()
- Added delays around resetSettings() calls to prevent ESP8266 WiFi stack crashes
- Reduced stress test iterations to avoid excessive output
- Improved test stability with better state checking and error handling

Total test count: 86 tests (up from 44)
All tests passing successfully

test/test_wifimanager/tests/test_state_transitions.cpp

@@ -0,0 +1,131 @@
+#include <unity.h>
+#include <Arduino.h>
+#include <WiFiManager.h>
+#include "../test_main.h"
+
+// Test portal to connected transition (state consistency)
+void test_portal_to_connected_transition() {
+    Serial.println("[TEST]   Testing portal to connected transition...");
+    
+    WiFiManager wm;
+    wm.setConfigPortalTimeout(10);
+    
+    // Start portal
+    wm.startConfigPortal("TestAP");
+    wm.process();
+    
+    // Verify portal is active
+    TEST_ASSERT_TRUE(wm.getConfigPortalActive());
+    TEST_ASSERT_FALSE(wm.getWebPortalActive());
+    
+    // Portal state should be consistent
+    // While portal is active, WiFi should be in AP mode
+    WiFiMode_t mode = WiFi.getMode();
+    TEST_ASSERT_TRUE((mode & WIFI_AP) != 0);
+    
+    // Stop portal
+    wm.stopConfigPortal();
+    wm.process();
+    
+    // Verify portal is stopped
+    TEST_ASSERT_FALSE(wm.getConfigPortalActive());
+    
+    Serial.println("[TEST]   Portal to connected transition test completed successfully");
+}
+
+// Test concurrent operations (portal + connection attempt)
+void test_concurrent_operations() {
+    Serial.println("[TEST]   Testing concurrent operations...");
+    
+    WiFiManager wm;
+    wm.setConfigPortalTimeout(10);
+    
+    // Start portal
+    wm.startConfigPortal("TestAP");
+    wm.process();
+    
+    TEST_ASSERT_TRUE(wm.getConfigPortalActive());
+    
+    // Attempt connection while portal is active (via preloadWiFi)
+    // This should either be ignored or handled gracefully
+    wm.preloadWiFi("NonExistentSSID_12345", "password");
+    
+    // Portal should still be active (connection attempt shouldn't stop it)
+    wm.process();
+    TEST_ASSERT_TRUE(wm.getConfigPortalActive());
+    
+    // Verify WiFi is not connected (SSID doesn't exist)
+    wl_status_t status = WiFi.status();
+    TEST_ASSERT_NOT_EQUAL(WL_CONNECTED, status);
+    
+    wm.stopConfigPortal();
+    
+    Serial.println("[TEST]   Concurrent operations test completed successfully");
+}
+
+// Test state consistency during portal operation
+void test_state_consistency_during_portal() {
+    Serial.println("[TEST]   Testing state consistency during portal operation...");
+    
+    WiFiManager wm;
+    wm.setConfigPortalTimeout(10);
+    
+    // Start portal
+    wm.startConfigPortal("TestAP");
+    wm.process();
+    
+    // Verify state consistency
+    TEST_ASSERT_TRUE(wm.getConfigPortalActive());
+    TEST_ASSERT_NOT_NULL(wm.server);
+    TEST_ASSERT_NOT_NULL(wm.dnsServer);
+    
+    // Process multiple times
+    for (int i = 0; i < 10; i++) {
+        wm.process();
+        delay(10);
+        
+        // State should remain consistent
+        TEST_ASSERT_TRUE(wm.getConfigPortalActive());
+    }
+    
+    wm.stopConfigPortal();
+    wm.process();
+    
+    // After stop, portal should be inactive
+    TEST_ASSERT_FALSE(wm.getConfigPortalActive());
+    
+    Serial.println("[TEST]   State consistency during portal operation test completed successfully");
+}
+
+// Test state transitions with multiple start/stop cycles
+void test_state_transitions_multiple_cycles() {
+    Serial.println("[TEST]   Testing state transitions with multiple cycles...");
+    
+    WiFiManager wm;
+    wm.setConfigPortalTimeout(10);
+    
+    for (int cycle = 0; cycle < 3; cycle++) {
+        // Start state
+        TEST_ASSERT_FALSE(wm.getConfigPortalActive());
+        
+        // Start portal
+        wm.startConfigPortal("TestAP");
+        wm.process();
+        TEST_ASSERT_TRUE(wm.getConfigPortalActive());
+        
+        // Active state
+        wm.process();
+        delay(100);
+        TEST_ASSERT_TRUE(wm.getConfigPortalActive());
+        
+        // Stop portal
+        wm.stopConfigPortal();
+        wm.process();
+        TEST_ASSERT_FALSE(wm.getConfigPortalActive());
+        
+        delay(100);
+    }
+    
+    Serial.println("[TEST]   State transitions with multiple cycles test completed successfully");
+}
+