tests: Add test scenario for BQ27441 battery gauge.

Add a YAML test scenario file `tests/scenarios/bq27441.yaml` for the BQ27441 driver.

### Expected tests
- **Mock**: verify device ID register
- **Hardware**: read state of charge, voltage, current, capacity
- **Manual**: validate displayed battery values

### Reference
- Driver: `lib/bq27441/`
- Test framework: PR #28