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_callback_firing.cpp

@@ -0,0 +1,129 @@
+#include <unity.h>
+#include <Arduino.h>
+#include <WiFiManager.h>
+#include "../test_main.h"
+
+// Callback flags (static to avoid duplicate definitions)
+static bool timeout_callback_fired = false;
+static bool config_reset_callback_fired = false;
+
+// Callback functions (static to avoid duplicate definitions)
+static void timeout_callback() {
+    timeout_callback_fired = true;
+}
+
+static void config_reset_callback() {
+    config_reset_callback_fired = true;
+}
+
+// Reset callback flags (static to avoid duplicate definitions)
+static void reset_callback_flags() {
+    timeout_callback_fired = false;
+    config_reset_callback_fired = false;
+}
+
+// Test timeout callback fires
+void test_timeout_callback_fires() {
+    Serial.println("[TEST]   Testing timeout callback firing...");
+    
+    reset_callback_flags();
+    
+    WiFiManager wm;
+    wm.setConfigPortalTimeoutCallback(timeout_callback);
+    
+    wm.setConfigPortalTimeout(2); // 2 second timeout
+    wm.startConfigPortal("TestAP");
+    
+    // Process until timeout
+    unsigned long start = millis();
+    while (wm.getConfigPortalActive() && (millis() - start < 5000)) {
+        wm.process();
+        delay(50);
+    }
+    
+    // Callback should have fired when timeout occurred
+    TEST_ASSERT_TRUE(timeout_callback_fired);
+    
+    wm.stopConfigPortal();
+    
+    Serial.println("[TEST]   Timeout callback firing test completed successfully");
+}
+
+// Test config reset callback fires
+void test_config_reset_callback_fires() {
+    Serial.println("[TEST]   Testing config reset callback firing...");
+    
+    reset_callback_flags();
+    
+    WiFiManager wm;
+    wm.setConfigResetCallback(config_reset_callback);
+    
+    // Ensure WiFi is in a stable state before resetting
+    delay(100);
+    
+    // Call resetSettings which should trigger callback
+    wm.resetSettings();
+    
+    // Allow WiFi operations to complete
+    delay(100);
+    
+    // Callback should have fired
+    TEST_ASSERT_TRUE(config_reset_callback_fired);
+    
+    Serial.println("[TEST]   Config reset callback firing test completed successfully");
+}
+
+// Test AP callback fires (improve existing test)
+void test_ap_callback_fires_improved() {
+    Serial.println("[TEST]   Testing AP callback firing (improved)...");
+    
+    bool ap_callback_fired = false;
+    
+    WiFiManager wm;
+    wm.setAPCallback([&](WiFiManager* wm) {
+        ap_callback_fired = true;
+        (void)wm; // Suppress unused parameter warning
+    });
+    
+    wm.setConfigPortalTimeout(5);
+    wm.startConfigPortal("TestAP");
+    wm.process();
+    
+    // Callback should have fired when AP starts
+    TEST_ASSERT_TRUE(ap_callback_fired);
+    
+    wm.stopConfigPortal();
+    
+    Serial.println("[TEST]   AP callback firing (improved) test completed successfully");
+}
+
+// Test web server callback fires (improve existing test)
+void test_web_server_callback_fires_improved() {
+    Serial.println("[TEST]   Testing web server callback firing (improved)...");
+    
+    bool web_server_callback_fired = false;
+    
+    WiFiManager wm;
+    wm.setWebServerCallback([&]() {
+        web_server_callback_fired = true;
+    });
+    
+    wm.setConfigPortalTimeout(5);
+    wm.startConfigPortal("TestAP");
+    wm.process();
+    
+    // Wait for server to initialize
+    unsigned long start = millis();
+    while (!web_server_callback_fired && (millis() - start < 1000)) {
+        wm.process();
+        delay(10);
+    }
+    
+    // Callback should have fired when server starts
+    TEST_ASSERT_TRUE(web_server_callback_fired);
+    
+    wm.stopConfigPortal();
+    
+    Serial.println("[TEST]   Web server callback firing (improved) test completed successfully");
+}
+