v1.12.2: flag CO2_ERROR (bit 7) quand la sonde S88 est deconnectee

A la demande: en plus du sentinel 0xFFFF dans le champ CO2, on remonte le
defaut via error_flags byte 66 bit 7.

- ERR_CO2 = 0x80 (bit 7, double sens vent/CO2 selon device_type cote serveur)
- s88_disconnected -> error_flags |= ERR_CO2 dans SARA_send_data_v2.py
- error_flags.md: bit 7 documente comme WIND_ERROR / CO2_ERROR

Confirme par le user: le serveur lit le bit 7 comme CO2_ERROR sur ces unites.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

loop/SARA_send_data_v2.py

@@ -160,6 +160,10 @@ ERR_ENVEA            = 0x10
 ERR_NOISE            = 0x20
 ERR_MPPT             = 0x40
 ERR_WIND             = 0x80
+# Bit 7 is dual-purpose per product (server decodes by device_type):
+#   NebuleAir -> WIND_ERROR, ModuleAir / CO2-equipped units -> CO2_ERROR.
+# On these CO2 boxes the server reads bit 7 as CO2_ERROR (confirmed).
+ERR_CO2              = 0x80
 
 # database connection
 conn = sqlite3.connect("/var/www/nebuleair_pro_4g/sqlite/sensors.db")
@@ -1087,8 +1091,9 @@ try:
     # Only transmit when the LAST reading is valid (s88_status == 0). If the
     # sensor is down (s88_status == 0xFF), leave bytes 81-82 at 0xFFFF (= "CO2
     # sensor absent" in the Miotiq spec) instead of sending a stale value.
-    # NB: byte 66 (error_flags) is already full, so absence is signalled solely
-    # by the 0xFFFF sentinel in the CO2 field.
+    # Absence is signalled two ways: the 0xFFFF sentinel in the CO2 field, and
+    # the CO2_ERROR bit (0x80) in error_flags (byte 66) — see build below.
+    s88_disconnected = False
     if s88_sensor:
         print("➡️Getting S88 CO2 value")
         cursor.execute("SELECT * FROM data_S88 ORDER BY rowid DESC LIMIT 1")
@@ -1100,9 +1105,11 @@ try:
                 print(f"CO2 (S88): {co2_ppm} ppm")
                 payload.set_co2(co2_ppm)
             else:
-                print(f"S88 last reading invalid (s88_status=0x{s88_status_value:02X}) -> CO2 marked absent (0xFFFF)")
+                s88_disconnected = True
+                print(f"S88 last reading invalid (s88_status=0x{s88_status_value:02X}) -> CO2 marked absent (0xFFFF), set CO2_ERROR")
         else:
-            print("No S88 data available in the database.")
+            s88_disconnected = True
+            print("No S88 data available in the database. -> set CO2_ERROR")
 
     #print("Verify SARA connection (AT)")
     
@@ -1236,6 +1243,8 @@ try:
         error_flags |= ERR_NPM
     if noise_disconnected:
         error_flags |= ERR_NOISE
+    if s88_disconnected:
+        error_flags |= ERR_CO2  # bit 7, read as CO2_ERROR by the server on these units
     payload.set_error_flags(error_flags)
 
     # ---- Firmware version (bytes 69-71) ----