릴리스: v1.4.33 가입 검증과 테마 기본값 정리

backend/src/db.js

@@ -575,6 +575,33 @@ async function findUserByEmail(email) {
   return { ...mapUserRow(row), passwordHash: row.password_hash }
 }
 
+async function findUserByNickname(nickname, excludeUserId = '') {
+  const normalized = String(nickname || '').trim()
+  if (!normalized) return null
+  const rows = excludeUserId
+    ? await query(
+        `
+          SELECT id, email, nickname, password_hash, is_admin, avatar_src, created_at
+          FROM users
+          WHERE TRIM(LOWER(nickname)) = TRIM(LOWER(?)) AND id <> ?
+          LIMIT 1
+        `,
+        [normalized, excludeUserId]
+      )
+    : await query(
+        `
+          SELECT id, email, nickname, password_hash, is_admin, avatar_src, created_at
+          FROM users
+          WHERE TRIM(LOWER(nickname)) = TRIM(LOWER(?))
+          LIMIT 1
+        `,
+        [normalized]
+      )
+  const row = rows[0]
+  if (!row) return null
+  return { ...mapUserRow(row), passwordHash: row.password_hash }
+}
+
 async function findUserById(id) {
   const rows = await query(
     'SELECT id, email, nickname, is_admin, avatar_src, created_at FROM users WHERE id = ? LIMIT 1',
@@ -2471,6 +2498,7 @@ module.exports = {
   closePool,
   countUsers,
   findUserByEmail,
+  findUserByNickname,
   findUserById,
   createUser,
   updateUserProfile,