Fix animation options field casting (#2713)

Fixes
https://youtrack.jetbrains.com/issue/CMP-9548/NullPointerException-in-KeyboardVisibilityListener-when-keyboard-notification-has-nil-userInfo

## Release Notes
### Fixes - iOS
- Fix crash when manually posting UIKeyboardWillHideNotification without
userInfo

Author: ASalavei

compose/ui/ui/src/iosMain/kotlin/androidx/compose/ui/window/KeyboardVisibilityListener.ios.kt

@@ -34,6 +34,7 @@ import platform.UIKit.UIKeyboardFrameEndUserInfoKey
 import platform.UIKit.UIKeyboardWillChangeFrameNotification
 import platform.UIKit.UIKeyboardWillHideNotification
 import platform.UIKit.UIKeyboardWillShowNotification
+import platform.UIKit.UIViewAnimationOptionCurveEaseInOut
 import platform.UIKit.UIViewAnimationOptions
 import platform.darwin.NSObject
 
@@ -143,6 +144,6 @@ private class NativeKeyboardVisibilityListener : NSObject() {
     private val NSNotification.animationOptions: UIViewAnimationOptions
         get() {
             val value = userInfo?.get(UIKeyboardAnimationCurveUserInfoKey) as? NSNumber
-            return value?.unsignedIntegerValue() as UIViewAnimationOptions
+            return value?.unsignedIntegerValue() ?: UIViewAnimationOptionCurveEaseInOut
         }
 }

compose/ui/ui/src/uikitInstrumentedTest/kotlin/androidx/compose/ui/keyboard/KeyboardNotificationsHandleTest.kt

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2026 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package androidx.compose.ui.keyboard
+
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.imePadding
+import androidx.compose.material.Text
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.test.runUIKitInstrumentedTest
+import kotlin.test.Test
+import platform.Foundation.NSNotificationCenter
+import platform.UIKit.UIKeyboardWillHideNotification
+import platform.UIKit.UIKeyboardWillShowNotification
+
+class KeyboardNotificationsHandleTest {
+    @Test
+    fun testKeyboardNotificationsHandle() = runUIKitInstrumentedTest {
+        setContent {
+            Text("Compose", modifier = Modifier.fillMaxSize().imePadding())
+        }
+
+        NSNotificationCenter.defaultCenter.postNotificationName(
+            UIKeyboardWillShowNotification,
+            null
+        )
+        waitForIdle()
+        // Should not crash
+
+        NSNotificationCenter.defaultCenter.postNotificationName(
+            UIKeyboardWillHideNotification,
+            null
+        )
+        waitForIdle()
+        // Should not crash
+    }
+}