fix(channel-donation): 후원 메시지 캔 수량을 천단위 콤마로 표시한다

src/main/kotlin/kr/co/vividnext/sodalive/explorer/profile/channelDonation/ChannelDonationService.kt

@@ -117,7 +117,8 @@ class ChannelDonationService(
         } else {
             "explorer.channel_donation.message.default.public"
         }
-        val defaultMessage = getMessage(key, can)
+        val formattedCan = String.format("%,d", can)
+        val defaultMessage = getMessage(key, formattedCan)
 
         return if (additionalMessage.isNullOrBlank()) {
             defaultMessage

src/test/kotlin/kr/co/vividnext/sodalive/explorer/profile/channelDonation/ChannelDonationControllerTest.kt

@@ -59,9 +59,9 @@ class ChannelDonationControllerTest {
             memberId = member.id!!,
             nickname = member.nickname,
             profileUrl = "https://cdn.test/profile/default-profile.png",
-            can = 3,
+            can = 1000,
             isSecret = false,
-            message = "3캔을 후원하셨습니다.",
+            message = "1,000캔을 후원하셨습니다.",
             createdAt = "2026-02-23T09:30:00"
         )
         val response = GetChannelDonationListResponse(totalCount = 1, items = listOf(item))

src/test/kotlin/kr/co/vividnext/sodalive/explorer/profile/channelDonation/ChannelDonationServiceTest.kt

@@ -110,6 +110,46 @@ class ChannelDonationServiceTest {
         )
     }
 
+    @Test
+    fun shouldFormatCanWithCommaInDonationMessage() {
+        val creator = createMember(id = 1L, role = MemberRole.CREATOR, nickname = "creator")
+        val viewer = createMember(id = 2L, role = MemberRole.USER, nickname = "viewer")
+        val message = ChannelDonationMessage(can = 1000, isSecret = true, additionalMessage = "응원합니다")
+        message.id = 1001L
+        message.member = viewer
+        message.creator = creator
+        message.createdAt = LocalDateTime.of(2026, 2, 20, 12, 0, 0)
+
+        Mockito.`when`(memberRepository.findCreatorByIdOrNull(creator.id!!)).thenReturn(creator)
+        Mockito.`when`(
+            channelDonationMessageRepository.getChannelDonationMessageTotalCount(
+                Mockito.eq(creator.id!!),
+                Mockito.eq(viewer.id!!),
+                Mockito.eq(false),
+                anyLocalDateTime()
+            )
+        ).thenReturn(1)
+        Mockito.`when`(
+            channelDonationMessageRepository.getChannelDonationMessageList(
+                Mockito.eq(creator.id!!),
+                Mockito.eq(viewer.id!!),
+                Mockito.eq(false),
+                Mockito.eq(0L),
+                Mockito.eq(5L),
+                anyLocalDateTime()
+            )
+        ).thenReturn(listOf(message))
+
+        val result = service.getChannelDonationList(
+            creatorId = creator.id!!,
+            member = viewer,
+            offset = 0,
+            limit = 5
+        )
+
+        assertEquals("1,000캔을 비밀후원하셨습니다.\n\"응원합니다\"", result.items[0].message)
+    }
+
     @Test
     fun shouldPassCreatorVisibilityFlagToRepositoryWhenRequesterIsCreatorSelf() {
         val creator = createMember(id = 1L, role = MemberRole.CREATOR, nickname = "creator")