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_basic.cpp

@@ -30,9 +30,15 @@ void test_reset_settings() {
     
     WiFiManager wm;
     
+    // Ensure WiFi is in a stable state before resetting
+    delay(100);
+    
     // Reset settings (should not crash)
     wm.resetSettings();
     
+    // Small delay to allow WiFi operations to complete
+    delay(100);
+    
     // Verify WiFi is not saved after reset
     // Note: ESP32 uses NVS for WiFi credentials which behaves differently than ESP8266's EEPROM
     // On ESP32, getWiFiIsSaved() may still return TRUE due to NVS persistence differences
@@ -58,10 +64,10 @@ void test_disconnect() {
     WiFiManager wm;
     
     // Disconnect should not crash even if not connected
-    bool result1 = wm.disconnect();
+    (void)wm.disconnect();
     
     // Can be called multiple times safely
-    bool result2 = wm.disconnect();
+    (void)wm.disconnect();
     
     // Verify no crash (results may be true/false depending on WiFi state)
     TEST_ASSERT_TRUE_MESSAGE(true, "disconnect() executed without crash");