fix: UndabangAvatar의 placeholder를 ic_profile_default로 변경 #517

- 기존: imageUrl이 null/blank면 Material Person 아이콘만 표시 (작고 어색)
- 변경: ic_profile_default drawable 사용, AsyncImage 로딩 실패 시에도 동일 drawable
- placeholderRes 파라미터로 override 가능

Author: edv-Shin

presentation/src/main/java/com/project200/presentation/compose/components/display/Avatar.kt

@@ -1,29 +1,29 @@
 package com.project200.presentation.compose.components.display
 
+import androidx.annotation.DrawableRes
+import androidx.compose.foundation.Image
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.shape.CircleShape
-import androidx.compose.material.icons.Icons
-import androidx.compose.material.icons.filled.Person
-import androidx.compose.material3.Icon
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.layout.ContentScale
+import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import coil.compose.AsyncImage
-import com.project200.presentation.compose.theme.ColorGray200
 import com.project200.presentation.compose.theme.ColorGray300
 import com.project200.presentation.compose.theme.ColorMain
+import com.project200.undabang.presentation.R
 
 /**
  * 원형 프로필 아바타
- * imageUrl이 null/blank면 Person 아이콘 placeholder를 표시합니다
+ * imageUrl이 null/blank거나 로딩 실패 시 placeholderRes drawable을 표시합니다
  */
 @Composable
 fun UndabangAvatar(
@@ -34,6 +34,7 @@ fun UndabangAvatar(
     borderWidth: Dp = 2.dp,
     placeholderBackground: Color = ColorGray300,
     contentDescription: String = "프로필 이미지",
+    @DrawableRes placeholderRes: Int = R.drawable.ic_profile_default,
 ) {
     Box(
         modifier =
@@ -48,22 +49,27 @@ fun UndabangAvatar(
                 ),
         contentAlignment = Alignment.Center,
     ) {
+        val innerModifier =
+            Modifier
+                .size(size - borderWidth * 2)
+                .clip(CircleShape)
+
         if (imageUrl.isNullOrBlank()) {
-            Icon(
-                imageVector = Icons.Default.Person,
+            Image(
+                painter = painterResource(placeholderRes),
                 contentDescription = contentDescription,
-                modifier = Modifier.size(size * 0.5f),
-                tint = ColorGray200,
+                contentScale = ContentScale.Crop,
+                modifier = innerModifier,
             )
         } else {
             AsyncImage(
                 model = imageUrl,
                 contentDescription = contentDescription,
-                modifier =
-                    Modifier
-                        .size(size - borderWidth * 2)
-                        .clip(CircleShape),
+                placeholder = painterResource(placeholderRes),
+                error = painterResource(placeholderRes),
+                fallback = painterResource(placeholderRes),
                 contentScale = ContentScale.Crop,
+                modifier = innerModifier,
             )
         }
     }