Ping aller-retour Miotiq: byte 9 = command, script ping + écoute réponse

- SensorPayload: byte 9 passe de protocol_version (0x01) à command (0x00 par défaut)
- Nouveau set_command() method (0x00=data normal, 0x01=ping test)
- Nouveau script SARA/sara_ping_miotiq.py: envoie payload 100 bytes avec command=1,
  puis écoute la réponse descendante Miotiq pendant 15s via AT+USORD
- Endpoint launcher.php sara_ping_miotiq
- Bouton "Ping Miotiq" dans la section tests Miotiq (page modem)
- Mise à jour error_flags.md avec la nouvelle map complète du payload

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

loop/SARA_send_data_v2.py

@@ -288,8 +288,8 @@ class SensorPayload:
         self.payload[66] = 0x00  # error_flags
         self.payload[67] = 0x00  # npm_status
         self.payload[68] = 0x00  # device_status
-        # Set protocol version (byte 9)
-        self.payload[9] = 0x01
+        # Byte 9: command (0x00 = data normal, 0x01 = ping test)
+        self.payload[9] = 0x00
     
     def set_signal_quality(self, value):
         """Set 4G signal quality (byte 8)"""
@@ -386,6 +386,10 @@ class SensorPayload:
         """Set device status flags (byte 68)"""
         self.payload[68] = status & 0xFF
 
+    def set_command(self, value):
+        """Set command byte (byte 9): 0x00 = normal data, 0x01 = ping test"""
+        self.payload[9] = value & 0xFF
+
     def set_firmware_version(self, version_str):
         """Set firmware version bytes 69-71 (major.minor.patch)"""
         try: