HEOS: Mark players unavailable on controller disconnection

[MarvinSchenkel]

What does this implement/fix?

When a HEOS-connected AVR is fully power-cycled, pyheos internally marks the device as unavailable, but Music Assistant was not listening for the disconnection event. This left the player showing as available in MA while the underlying transport connection was gone, causing every playback command to fail with CommandError: Not connected to device until the MA addon was restarted.

The fix subscribes to pyheos's add_on_disconnected callback in _setup_controllers. When the callback fires, set_device_info() is called on each registered HEOS player, which reads the (now-False) available attribute from the pyheos device object and propagates it via update_state(). Recovery on reconnection was already handled correctly: pyheos fires EVENT_PLAYERS_CHANGED with a PlayerUpdateResult after reloading players, which triggers the existing _handle_controller_event → discover_players() path.

Related issue (if applicable):

• related issue Player remains available after AVR power-off; playback fails with “Not connected to device” until Music Assistant restart (HEOS + DLNA) support#5565

Types of changes

• Bugfix (non-breaking change which fixes an issue) — bugfix

Checklist

• The code change is tested and works locally.
• pre-commit run --all-files passes.
• pytest passes, and tests have been added/updated under tests/ where applicable.
• For changes to shared models, the companion PR in music-assistant/models is linked.
• For changes affecting the UI, the companion PR in music-assistant/frontend is linked.
• I have read and complied with the project's AI Policy for any AI-assisted contributions.
• I have raised a PR against the documentation repository targeting the main or beta branch as appropriate.

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[MarvinSchenkel]

@Tommatheussen my issues agent came up with this fix, could you sanity check this please?

[Copilot]

Pull request overview

This PR improves the HEOS player provider’s connection lifecycle handling by reacting to pyheos controller disconnection events so Music Assistant immediately reflects HEOS players as unavailable after an AVR power-cycle/disconnect.

Changes:

• Subscribes to pyheos add_on_disconnected during controller setup.
• Adds a disconnection callback that refreshes each HEOS player’s device info and pushes an updated state so availability is propagated promptly.

[Tommatheussen]

LGTM, I can test on phyiscal devices later today if you want

[MarvinSchenkel]

Would be great since I do not have any :)

[Tommatheussen]

@MarvinSchenkel technically, the changes are correct, the problem is a bit deeper though. pyheos doesn't invoke the _on_disconnected all that often, seems to happen mainly when we programmatically disconnect (so a known disconnection), or when the device gets rebooted. Basically when the connection really gets cleanly closed.
Seems turning off the AVR doesn't properly close the connection, resulting in commands timing out instead. This timeout doesn't trigger the callback.
I'll check with the pyheos creator if this is intented or not, to me it makes sense that commands timing out (at least connection heartbeat commands) would indicate a broken connection.