Debug-Test1

Fix: Correct checksum calculation for AirTouch2+ messages

The AirTouch2+ controller requires the CRC checksum to be calculated from the address field to the end of the data payload. The previous implementation used an incorrect offset, resulting in invalid checksums and causing the controller to reject messages and lock out the client.

This commit corrects the checksum calculation in `message_common.py` to use the proper starting offset (`CommonMessageOffsets.ADDRESS`).

It also adds the `get_data_from_offset` method to the `Buffer` class, which was necessary to support the corrected checksum logic and resolve a subsequent `AttributeError`.