[SENSOR] Build CO2 sensor with drift simulation

[ezehf2]

Create co2_sensor.py, extending the sensor base class. CO2 levels should drift gradually between 400 ppm (fresh air) and 1500 ppm (poor air quality). The alert threshold defined in the project is 1000 ppm, so the simulation should be capable of reaching and exceeding that level naturally over time. Include a short manual test printing five consecutive readings to demonstrate drift behaviour.