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_static_ip.cpp

@@ -22,6 +22,8 @@ void test_set_ap_static_ip_config() {
     wm.startConfigPortal("TestAP");
     TEST_ASSERT_TRUE(wm.getConfigPortalActive());
     
+    // Call process() to simulate real usage
+    wm.process();
     delay(200); // Give time for IP to be configured
     
     // Verify AP IP matches what we configured
@@ -75,6 +77,8 @@ void test_ap_static_ip_application() {
     wm.startConfigPortal("TestAP");
     TEST_ASSERT_TRUE(wm.getConfigPortalActive());
     
+    // Call process() to simulate real usage
+    wm.process();
     delay(200); // Give time for AP to configure
     
     IPAddress apIP = WiFi.softAPIP();