feat: intégration capteur CO2 MH-Z19

- Scripts MH-Z19/get_data.py (lecture standalone) et write_data.py (écriture SQLite)
- Table data_MHZ19, config MHZ19, cleanup et service systemd (120s)
- Web UI : carte test sensors, checkbox admin, boutons database + CSV download
- SARA_send_data_v2.py non modifié (sera fait dans un second temps)

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

MH-Z19/write_data.py

@@ -0,0 +1,66 @@
+'''
+Script to get CO2 values from MH-Z19 sensor and write to database
+/usr/bin/python3 /var/www/nebuleair_pro_4g/MH-Z19/write_data.py
+'''
+
+import serial
+import json
+import sys
+import time
+import sqlite3
+
+conn = sqlite3.connect("/var/www/nebuleair_pro_4g/sqlite/sensors.db")
+cursor = conn.cursor()
+
+mh_z19_port = "/dev/ttyAMA4"
+
+ser = serial.Serial(
+    port=mh_z19_port,
+    baudrate=9600,
+    parity=serial.PARITY_NONE,
+    stopbits=serial.STOPBITS_ONE,
+    bytesize=serial.EIGHTBITS,
+    timeout=1
+)
+
+READ_CO2_COMMAND = b'\xFF\x01\x86\x00\x00\x00\x00\x00\x79'
+
+
+def read_co2():
+    ser.write(READ_CO2_COMMAND)
+    time.sleep(2)
+    response = ser.read(9)
+    if len(response) < 9:
+        print("Error: No data or incomplete data received from CO2 sensor.")
+        return None
+    if response[0] == 0xFF:
+        co2_concentration = response[2] * 256 + response[3]
+        return co2_concentration
+    else:
+        print("Error reading data from CO2 sensor.")
+        return None
+
+
+def main():
+    try:
+        co2 = read_co2()
+        if co2 is not None:
+            # Get RTC time from SQLite
+            cursor.execute("SELECT * FROM timestamp_table LIMIT 1")
+            row = cursor.fetchone()
+            rtc_time_str = row[1]
+            # Save to SQLite
+            cursor.execute('INSERT INTO data_MHZ19 (timestamp, CO2) VALUES (?, ?)', (rtc_time_str, co2))
+            conn.commit()
+            print(f"CO2: {co2} ppm (saved at {rtc_time_str})")
+        else:
+            print("Failed to get CO2 data.")
+    except KeyboardInterrupt:
+        print("Program terminated.")
+    finally:
+        ser.close()
+        conn.close()
+
+
+if __name__ == '__main__':
+    main()