fix: 토스트 다크모드 완전 지원

- 배경색을 반투명 회색(#CC333333)으로 변경하여 라이트/다크 모두 가독성 확보
- 텍스트 색상을 흰색(@android:color/white)으로 변경
- showCustomToast() 함수 개선

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/AlarmUtils.kt

@@ -29,6 +29,27 @@ fun showCustomToast(context: Context, message: String, duration: Int = android.w
  val toast = android.widget.Toast(context)
  toast.duration = duration
  toast.view = layout
+ toast.setGravity(android.view.Gravity.BOTTOM or android.view.Gravity.CENTER_HORIZONTAL, 0, 150)
+ toast.show()
+ } catch (e: Exception) {
+ // Fallback to default toast if custom toast fails
+ android.widget.Toast.makeText(context, message, duration).show()
+ }
+}
+ * 다크모드 지원 커스텀 토스트 표시
+ */
+fun showCustomToast(context: Context, message: String, duration: Int = android.widget.Toast.LENGTH_SHORT) {
+ try {
+ // Use application context with theme for proper dark mode support
+ val themedContext = android.view.ContextThemeWrapper(context.applicationContext, R.style.Theme_ShiftAlarm)
+ val inflater = android.view.LayoutInflater.from(themedContext)
+ val layout = inflater.inflate(R.layout.custom_toast, null)
+ val textView = layout.findViewById<android.widget.TextView>(R.id.toastText)
+ textView.text = message
+
+ val toast = android.widget.Toast(context.applicationContext)
+ toast.duration = duration
+ toast.view = layout
  toast.setGravity(android.view.Gravity.BOTTOM or android.view.Gravity.CENTER_HORIZONTAL, 0, 100)
  toast.show()
  } catch (e: Exception) {