feat(member): 회원 썸네일 업로드를 WebP 리사이즈로 표준화

회원 아바타 업로드 시 원본 포맷을 WebP로 변환하고 최대 해상도/품질을 환경변수로 제어해 저장 용량과 전송 비용을 줄인다.

Co-authored-by: Cursor <cursoragent@cursor.com>

server/api/auth/avatar.post.js

@@ -1,7 +1,8 @@
 import { randomUUID } from 'node:crypto'
 import { mkdir, writeFile } from 'node:fs/promises'
-import { extname, join } from 'node:path'
+import { join } from 'node:path'
 import { createError, readMultipartFormData } from 'h3'
+import sharp from 'sharp'
 import { getPostgresClient } from '../../repositories/postgres-client'
 import { updateMemberProfile, getUserById } from '../../repositories/member-repository'
 import { requireMemberSession } from '../../utils/member-auth'
@@ -24,21 +25,6 @@ const sanitizePathPart = (value) => value
   .replace(/-+/g, '-')
   .replace(/^-|-$/g, '')
 
-/**
- * 파일 확장자 조회
- * @param {Object} file - multipart 파일 파트
- * @returns {string} 확장자
- */
-const getUploadExtension = (file) => {
-  const extension = extname(file.filename || '').toLowerCase()
-
-  if (allowedImageTypes.has(file.type)) {
-    return allowedImageTypes.get(file.type)
-  }
-
-  return extension
-}
-
 /**
  * 회원 썸네일 업로드 API
  * @param {import('h3').H3Event} event - 요청 이벤트
@@ -56,6 +42,9 @@ export default defineEventHandler(async (event) => {
 
   const config = useRuntimeConfig()
   const maxFileSize = Number(config.maxFileSize || 10485760)
+  const avatarMaxWidth = Number(config.avatarMaxWidth || 512)
+  const avatarMaxHeight = Number(config.avatarMaxHeight || 512)
+  const avatarWebpQuality = Number(config.avatarWebpQuality || 82)
   const formData = await readMultipartFormData(event)
   const file = (formData || []).find((part) => part.name === 'file' && part.filename)
 
@@ -90,12 +79,32 @@ export default defineEventHandler(async (event) => {
   await mkdir(directoryPath, { recursive: true })
 
   const originalName = sanitizePathPart(file.filename.replace(/\.[^.]+$/g, '')) || 'avatar'
-  const extension = getUploadExtension(file)
-  const fileName = `${originalName}-${randomUUID()}${extension}`
+  const fileName = `${originalName}-${randomUUID()}.webp`
   const filePath = join(directoryPath, fileName)
   const avatarUrl = `${uploadBaseUrl}/members/avatars/${year}/${month}/${fileName}`
+  const metadata = await sharp(file.data).metadata()
 
-  await writeFile(filePath, file.data)
+  if (!metadata.width || !metadata.height) {
+    throw createError({
+      statusCode: 400,
+      message: '이미지 메타데이터를 읽을 수 없습니다.'
+    })
+  }
+
+  const resizedBuffer = await sharp(file.data)
+    .rotate()
+    .resize({
+      width: avatarMaxWidth,
+      height: avatarMaxHeight,
+      fit: 'inside',
+      withoutEnlargement: true
+    })
+    .webp({
+      quality: avatarWebpQuality
+    })
+    .toBuffer()
+
+  await writeFile(filePath, resizedBuffer)
 
   await updateMemberProfile({
     userId: session.userId,