MadVR Envy Integration

To Power On your envy, wol has to be enabled on motherboard.

Thanks @Peter . WOL is enabled by default on all MadVR Envy devices.

Fixes done based on recent learnings from integration fixed where i could test - expanding learnings to blind integrations. Test at will.

Setup checks the connection before saving anything, so a failed test no longer overwrites a working configuration. Errors show on the form, and what you typed is kept.
Entity IDs stay the same when the Envy's IP changes, so activities and button mappings keep working.
Running setup again replaces the old connection instead of leaving it running next to the new one.
A command the Envy rejects no longer marks it as in standby.
An Envy that is in standby when the integration starts now shows as off instead of unknown.
Power on without a known MAC address returns an error instead of a false OK.
Remote:
repeat/delay and command sequences now work;
commands the Envy rejects return an error.
A lost connection while the Envy is in standby is logged once instead of every few seconds.
Docker: the container now starts. Before, the start command failed.