Feature request: expose active SOURCE profile as a sensor/select entity

[lsimek41-blip]

First off, thanks for this integration — activate_profile works great and I'm using it in an automation that syncs my madVR profile with an external audio processor's HDMI input selection.

"The gap:" there's currently no way to read back which SOURCE profile is currently active on the Envy. This is especially noticeable when the profile is changed manually via the Envy's own RC2 remote (Profile → Source Devices → ...) — Home Assistant has no way of knowing this happened, so anything downstream that needs to stay in sync (like my AVR input automation) breaks.

"Technical basis:" per the Envy IP Control spec, Envy already broadcasts this on every profile change, whether triggered automatically, via IP command, or manually via remote:

ActivateProfile SOURCE %profileId% ⏎

There's also a direct query/response pair for polling on connect:

GetActiveProfile SOURCE ⏎
ActiveProfile SOURCE %activeProfileIndex% ⏎

"Suggestion:"since py-madvr-envy already implements enum_profile_groups_collect() / enum_profiles_collect(), it seems like parsing the ActivateProfile notification into a sensor (or select, mirroring the existing activate_profile action) would be a natural complement — something like sensor.<device>_active_source_profile, updated both on the push notification and via an initial GetActiveProfile query on connect/reconnect.

Happy to help test this if useful — I have an Envy Extreme MK3 with several named source profiles I can validate against.

[lsimek41-blip]

One more related gap while I'm at it: same issue applies to remote control button presses (KeyPress/KeyHold notifications from the physical RC2 remote), not just Source profile changes.

Per the IP Control spec, Envy broadcasts this on every button press, regardless of whether a menu is open:

KeyPress|KeyHold %ButtonName% ⏎

Supported buttons include UP/DOWN, which I'd like to use to drive an external device (volume control) via a Home Assistant automation — but there's currently no way to observe these presses in HA, since the integration only supports sending KeyPress commands via remote.send_command, not receiving/exposing them.

Curious whether the underlying py-madvr-envy library already parses these notifications internally (given the "full protocol coverage" claim in the docs) — if so, this might just be a matter of wiring that up to fire an HA event (e.g. madvr_envy_key_pressed with a button payload), rather than needing new protocol parsing. Happy to test on my Extreme MK3 if that helps.