Redesign HA cards with fill-based backgrounds and add media player

Navigation: arrow keys now always navigate the card grid (removed
left/right value adjustment from Range/Climate cards). Scroll wheel
on the Magic Remote adjusts range values instead.

Cards: 4-column layout with taller (160px) cards. Each card shows a
fill bar proportional to its value — brightness for lights, target
temperature for climate, volume for media. State-based accent colors
(warm yellow for lights, orange/red for heating, blue for cooling,
purple for media playback).

New card type: Media (media_player) — shows artist, track title,
volume fill, and album art placeholder. OK toggles play/pause,
scroll wheel adjusts volume.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/ha_client.rs

@@ -440,6 +440,10 @@ pub fn entity_ids_from_config(config: &Value) -> Vec<String> {
         }
     }
 
+    if let Some(media) = config.get("media").and_then(|m| m.get("entity_id")).and_then(Value::as_str) {
+        ids.push(media.to_owned());
+    }
+
     if let Some(rooms) = config.get("rooms").and_then(Value::as_array) {
         for room in rooms {
             if let Some(sensors) = room.get("sensors").and_then(Value::as_array) {