[TESTING] Write unit tests for noise and occupancy sensors

[ezehf2]

Create tests/test_noise_sensor.py and tests/test_occupancy_sensor.py. Each file must test four things — that generate_reading() returns valid JSON, that all required fields are present (sensor_type, room, value, unit, timestamp), that the value falls within the expected range (noise 30–100 dB, occupancy 0 to room capacity), and that drift between consecutive readings does not exceed a reasonable step (noise max 5 dB per reading, occupancy max 3 people per reading). Run with pytest tests/ and paste the passing output as a comment on this issue before closing.

[mbaj2]