Update factory reset procedure in README and main.cpp for clarity and functionality

src/main.cpp

@@ -613,7 +613,7 @@ static void startServer() {
 }
 
 // ---------------------------------------------------------------------------
-// Factory reset (hold BOOT button 3s at startup)
+// Factory reset (rapid reset 5× within a few seconds)
 // ---------------------------------------------------------------------------
 
 static void factoryReset() {
@@ -699,19 +699,25 @@ static void factoryReset() {
 }
 
 static void checkFactoryReset() {
-  pinMode(0, INPUT_PULLUP);
-  delay(10);
-  if (digitalRead(0) == LOW) {
-    Serial.println("[BOOT] BOOT button held, hold 3s for factory reset...");
-    unsigned long start = millis();
-    while (millis() - start < 3000) {
-      delay(50);
-      if (digitalRead(0) != LOW) {
-        Serial.println("[BOOT] factory reset aborted (button released)");
-        return;
-      }
-    }
+  const int THRESHOLD = 5;
+  int count = 0;
+  File f = LittleFS.open("/reset_count", "r");
+  if (f) {
+    count = f.parseInt();
+    f.close();
+  }
+  count++;
+  if (count >= THRESHOLD) {
+    LittleFS.remove("/reset_count");
+    Serial.printf("[BOOT] reset count %d, triggering factory reset\n", count);
     factoryReset();
+    return;
+  }
+  f = LittleFS.open("/reset_count", "w");
+  if (f) {
+    f.print(count);
+    f.close();
+    Serial.printf("[BOOT] reset count %d/%d\n", count, THRESHOLD);
   }
 }
 
@@ -754,6 +760,7 @@ void setup() {
   startMDNS();
   mqttReconnectAt = 0;
 
+  LittleFS.remove("/reset_count");
   Serial.printf("[BOOT] ready at http://%s.local or http://%s\n",
                 hostname, WiFi.localIP().toString().c_str());
 }