Fix C1000 Gen 2 subscribe using the new send_command interface

[alec-pinson]

_post_connect still calls _send_command with the pre-#61 signature (cmd as bytes, payload=), so the required parameters argument is never supplied:

File "SolixBLE/devices/c1000g2.py", line 62, in _post_connect
    await self._send_command(
TypeError: _send_command() missing 1 required positional argument: 'parameters'

connect() catches this, so the connection survives but the subscribe is never sent — and the Gen 2 streams no telemetry without it. Every sensor reads unavailable. Regression from 685573a, first released in 4.0.0b1.

The raw payload a10121 is parameter a1 with value 21, so it maps directly onto the new interface and the bytes on the wire are unchanged from 3.9.0.

Adds a command test asserting the subscribe builds cmd 4100 with payload a10121. It fails with the above TypeError without the fix.

Reproduced and verified on a real C1000 Gen 2 (A1763).

[ladamczyk-it]

Tested on a second C1000 Gen 2 (A1763): with 4.0.0b1 _post_connect fails as described and no telemetry is received. Sending the subscribe as _send_command(cmd="4100", parameters={"a1": {"value": "21"}}) fixes it: the station starts streaming c421/c900 telemetry immediately and all sensors decode correctly.

Note: my unit has newer firmware (capability byte 04), so it also needed the encrypted handshake from #70 to get past negotiation. With both changes it works end-to-end.

[flip-dots]

Thanks, bit of an oversight on my part (that’s what I get for meh test coverage i guess), I appreciate the fix.