Firmware : IMU BLE désactivé en mode production (debug OFF)

L'envoi Roll/Pitch/Yaw sur imuChar est maintenant conditionné à
debugMode != OFF → charge BLE réduite pour Unreal en production.
Le calibration tool Python (debug FULL) continue de recevoir l'IMU.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Arduino/PS_BLE_ShotDetection/PS_BLE_ShotDetection.ino

@@ -574,8 +574,9 @@ void loop() {
   sendDebugData(accelMag, gyroMag, audioLevel);
   printDebugSerial(accelMag, gyroMag, audioLevel);
 
-  // ─── IMU BLE 10 Hz ───
-  if (now-lastSend>=100) {
+  // ─── IMU BLE 10 Hz (debug uniquement) ───
+  // En production (debugMode OFF), pas d'envoi IMU → charge BLE réduite pour Unreal
+  if (debugMode != DEBUG_OFF && now-lastSend>=100) {
     lastSend=now;
     float dt=(now-lastUpdate)/1000.0f; lastUpdate=now;
     roll+=gx*dt; pitch+=gy*dt; yaw+=gz*dt;