feat(playlists): expose scene playlists as Home Assistant entities

One device per scene playlist (model "Scene Playlist"), each with:
- a switch (start/stop; the server cycles one playlist at a time, so starting one stops any other)
- a "Current Scene" sensor that resolves the active preset name from scene_presets while this playlist is cycling
- an "Items" diagnostic sensor (configured scene count; no state_class)

The coordinator reads scene_playlists plus the flat playlist_state from the /api/v1/snapshot payload and gains start_playlist()/stop_playlist(); __init__ registers and prunes per-playlist devices and reloads on playlist-id changes; the event listener also refreshes on the playlist_state_changed WS event. Shared device/lookup/running-state plumbing lives in a new LedGrabPlaylistEntity base (entity.py) used by both the switch and the sensors. Adds en/ru translation keys.

Note: this also lands the in-progress coordinator migration from the per-request fan-out to the single /api/v1/snapshot poll that was already present in the working tree.

Requires the led-grab server /api/v1/snapshot to emit scene_playlists + playlist_state (companion server change, tracked separately).

custom_components/ledgrab/__init__.py

@@ -113,6 +113,22 @@ async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
         )
         current_identifiers.add(scenes_identifier)
 
+    # One device per scene playlist — groups its switch + stats sensors.
+    scene_playlists = (
+        coordinator.data.get("scene_playlists", []) if coordinator.data else []
+    )
+    for playlist in scene_playlists:
+        playlist_identifier = (DOMAIN, playlist["id"])
+        device_registry.async_get_or_create(
+            config_entry_id=entry.entry_id,
+            identifiers={playlist_identifier},
+            name=playlist.get("name", playlist["id"]),
+            manufacturer=server_name,
+            model="Scene Playlist",
+            configuration_url=server_url,
+        )
+        current_identifiers.add(playlist_identifier)
+
     # One device per sync clock — groups its switch/number/button/sensor.
     sync_clocks = coordinator.data.get("sync_clocks", []) if coordinator.data else []
     for clock in sync_clocks:
@@ -140,37 +156,45 @@ async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
         DATA_EVENT_LISTENER: event_listener,
     }
 
-    # Track target, scene, and sync-clock IDs to detect changes
+    # Track target, scene, playlist, and sync-clock IDs to detect changes
     known_target_ids = set(coordinator.data.get("targets", {}).keys() if coordinator.data else [])
     known_scene_ids = set(
         p["id"] for p in (coordinator.data.get("scene_presets", []) if coordinator.data else [])
     )
+    known_playlist_ids = set(
+        p["id"] for p in (coordinator.data.get("scene_playlists", []) if coordinator.data else [])
+    )
     known_clock_ids = set(
         c["id"] for c in (coordinator.data.get("sync_clocks", []) if coordinator.data else [])
     )
 
     def _on_coordinator_update() -> None:
-        """Detect target/scene/clock list changes and trigger reload."""
-        nonlocal known_target_ids, known_scene_ids, known_clock_ids
+        """Detect target/scene/playlist/clock list changes and trigger reload."""
+        nonlocal known_target_ids, known_scene_ids, known_playlist_ids, known_clock_ids
 
         if not coordinator.data:
             return
 
         targets = coordinator.data.get("targets", {})
 
-        # Reload if target, scene, or sync-clock list changed
+        # Reload if target, scene, playlist, or sync-clock list changed
         current_ids = set(targets.keys())
         current_scene_ids = set(p["id"] for p in coordinator.data.get("scene_presets", []))
+        current_playlist_ids = set(p["id"] for p in coordinator.data.get("scene_playlists", []))
         current_clock_ids = set(c["id"] for c in coordinator.data.get("sync_clocks", []))
         if (
             current_ids != known_target_ids
             or current_scene_ids != known_scene_ids
+            or current_playlist_ids != known_playlist_ids
             or current_clock_ids != known_clock_ids
         ):
             known_target_ids = current_ids
             known_scene_ids = current_scene_ids
+            known_playlist_ids = current_playlist_ids
             known_clock_ids = current_clock_ids
-            _LOGGER.info("Target, scene, or sync-clock list changed, reloading integration")
+            _LOGGER.info(
+                "Target, scene, playlist, or sync-clock list changed, reloading integration"
+            )
             hass.async_create_task(hass.config_entries.async_reload(entry.entry_id))
 
     coordinator.async_add_listener(_on_coordinator_update)