feat: 달력 월 이동 애니메이션 개선

- AccelerateDecelerateInterpolator 적용으로 자연스러운 가속/감속 곡선 구현
- 스케일 효과(scaleX/scaleY 0.95) 추가로 깊이감 있는 화면 전환
- 애니메이션 지속시간 200ms → 280ms로 조정
- 알파 페이드 0.5 → 0.7로 조정하여 가독성 향상

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

app/src/main/java/com/example/shiftalarm/MainActivity.kt

@@ -10,6 +10,7 @@ import android.os.Build
 import android.os.Bundle
 import android.view.GestureDetector
 import android.view.MotionEvent
+import android.view.animation.AccelerateDecelerateInterpolator
 import android.widget.Toast
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.app.ActivityCompat
@@ -708,7 +709,7 @@ class MainActivity : AppCompatActivity() {
     private fun animateMonthTransition(direction: Int) {
         val card = binding.calendarCard
         val width = card.width.toFloat()
-        
+
         if (width == 0f) {
             currentViewMonth = if (direction > 0) {
                 currentViewMonth.plusMonths(1)
@@ -718,11 +719,14 @@ class MainActivity : AppCompatActivity() {
             updateCalendar()
             return
         }
-        
+
         card.animate()
             .translationX(if (direction > 0) -width else width)
-            .alpha(0.5f)
+            .alpha(0.7f)
-            .setDuration(200)
+            .scaleX(0.95f)
+            .scaleY(0.95f)
+            .setDuration(280)
+            .setInterpolator(AccelerateDecelerateInterpolator())
             .withEndAction {
                 currentViewMonth = if (direction > 0) {
                     currentViewMonth.plusMonths(1)
@@ -730,12 +734,18 @@ class MainActivity : AppCompatActivity() {
                     currentViewMonth.minusMonths(1)
                 }
                 updateCalendar()
-                
+
                 card.translationX = if (direction > 0) width else -width
+                card.scaleX = 0.95f
+                card.scaleY = 0.95f
+
                 card.animate()
                     .translationX(0f)
                     .alpha(1f)
-                    .setDuration(200)
+                    .scaleX(1f)
+                    .scaleY(1f)
+                    .setDuration(280)
+                    .setInterpolator(AccelerateDecelerateInterpolator())
                     .start()
             }
             .start()