Add Gardena mower protocol features

[AlirezaT]

This ports the generic Automower/Gardena BLE protocol work from the Home Assistant Gardena BLE integration back into the Python library.

Included:

• safer command response helpers that expose mower response results
• serialized locked command flow for multi-step commands
• keep-alive task cleanup on disconnect
• schedule transaction helpers for reading, replacing, and clearing weekly tasks
• Gardena-compatible SpotCut flow: prepare SpotCut, start timed override, then trigger start
• additional protocol definitions for battery diagnostics, SensorControl/frost sensor, drive-past-wire, starting points, reversing distance, SpotCut, realtime sensor data, signal quality, firmware/hardware identity, and production info
• parser support for signed 16-bit values and variable trailing integer fields, so GetTask works with both existing upstream fixtures and Gardena responses

Notes:

• The new commands were tested from the Home Assistant integration against a Gardena Sileno mower and cross-checked with Gardena app BLE/HCI observations where available.
• Some commands are model-dependent and may return NOT_AVAILABLE, INVALID_ID, or NOT_ALLOWED on mowers that do not expose that feature.

Validation:

• python -m unittest discover
• python -m compileall automower_ble tests
• git diff --check

[alistair23]

Do we really need a lock here?

[alistair23]

Sorry about the long delay!

Overall this looks good. It does need a rebase and the ruff CI tests need to pass.

It would be great (although not required) if you could split the PR up into some smaller independent PRs. That way if something breaks it's easy to figure out exactly what change causes the breakage.

I'm also not clear on why we need

safer command response helpers that expose mower response results
serialized locked command flow for multi-step commands

Can you provide a few more details?