Android UI - Fix adapter observer lifecycle

Move carousel observer registration to setAdapter() so it is bound to the adapter lifecycle. This prevents repeated observer registration during carousel setup and eliminates duplicate refresh and focus callbacks after changes to the view type.

src/android/app/src/main/java/org/yuzu/yuzu_emu/views/CarouselRecyclerView.kt

@@ -55,6 +55,16 @@ class CarouselRecyclerView @JvmOverloads constructor(
     private val preferences =
         PreferenceManager.getDefaultSharedPreferences(YuzuApplication.appContext)
 
+    private val carouselAdapterObserver = object : RecyclerView.AdapterDataObserver() {
+        override fun onChanged() {
+            if (!pendingScrollAfterReload) return
+                doOnNextLayout {
+                    refreshView()
+                    pendingScrollAfterReload = false
+                }
+            }
+        }
+
     var flingMultiplier: Float = 1f
 
     var pendingScrollAfterReload: Boolean = false
@@ -70,6 +80,18 @@ class CarouselRecyclerView @JvmOverloads constructor(
         setChildrenDrawingOrderEnabled(true)
     }
 
+    override fun setAdapter(adapter: Adapter<*>?) {
+        val oldAdapter = this.adapter as? GameAdapter
+
+        if (oldAdapter !== adapter) {
+            oldAdapter?.unregisterAdapterDataObserver(carouselAdapterObserver)
+        }
+
+        super.setAdapter(adapter)
+
+        (adapter as? GameAdapter)?.registerAdapterDataObserver(carouselAdapterObserver)
+    }
+
     private fun calculateCenter(width: Int, paddingStart: Int, paddingEnd: Int): Int {
         return paddingStart + (width - paddingStart - paddingEnd) / 2
     }
@@ -252,17 +274,6 @@ class CarouselRecyclerView @JvmOverloads constructor(
                 internalFlingMultiplier
             ).coerceIn(1f, 5f)
 
-            gameAdapter .registerAdapterDataObserver(object : RecyclerView.AdapterDataObserver() {
-                override fun onChanged() {
-                    if (pendingScrollAfterReload) {
-                        doOnNextLayout {
-                            refreshView()
-                            pendingScrollAfterReload = false
-                        }
-                    }
-                }
-            })
-
             // Detach SnapHelper during setup
             pagerSnapHelper?.attachToRecyclerView(null)