v1.7.1: Detection SIM injoignable avant escalade hardware reboot

- Nouvelle fonction check_sim_status() (AT+CPIN? + AT+CCID)
- Branche d'echec PDP: diagnostic SIM avant reboot hardware
- Logs HTML tres visibles si SIM absente (bordure rouge, action claire)
- Notification WiFi dediee: 'SIM NOT DETECTED -> physical check required'
- Zero impact happy path: check uniquement quand PDP reset echoue

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

VERSION

@@ -1 +1 @@
-1.7.0
+1.7.1