fix: replace deprecated async_track_state_change with async_track_state_change_event

[r0bb10]

Async_track_state_change was deprecated in HA 2025.5 and scheduled for removal. This fix uses async_track_state_change_event on supported HA versions while falling back to the old function on older instances.

Adds a try/except import for forward compatibility and an event adapter wrapper that extracts entity_id/old_state/new_state from the Event object to reuse the existing callback logic unchanged.

[andbad]

Hi, thanks for tackling this deprecation but there are a couple of issues that prevent merging as-is.

1. Unconditional import of async_track_state_change

In the except ImportError branch you set async_track_state_change_event = None, but then immediately import async_track_state_change unconditionally (outside the except block). On HA ≥ 2025.5 that function has been removed, so the import will raise ImportError on exactly the instances this fix is supposed to support.

2. The if async_track_state_change_event branch in the call site

Scattering the version check across every registration point makes the code fragile: any future call site would need the same if/else duplicated. The cleaner pattern is to keep the shim entirely inside the except block so async_track_state_change_event is always a valid callable, and the rest of the code stays uniform.

A working fallback would look like this:

try:
    from homeassistant.helpers.event import async_track_state_change_event
except ImportError:
    from homeassistant.helpers.event import async_track_state_change as _legacy

    class _LegacyEvent:
        def __init__(self, entity_id, old_state, new_state):
            self.data = {"entity_id": entity_id, "old_state": old_state, "new_state": new_state}

    def async_track_state_change_event(hass, entity_ids, action):
        @callback
        def _wrap(entity_id, old_state, new_state):
            action(_LegacyEvent(entity_id, old_state, new_state))
        return _legacy(hass, entity_ids, _wrap)

With this shim in place, the call site needs no conditional at all. Let me know

By(t)e