fix(migrate): 兑换迁移码在双方认领锁下检查目标配额，超出返回 403 migrate_quota_exceeded 且码不消耗

panel/src/i18n/resources/en-US/errors.json

@@ -79,6 +79,7 @@
   "account_retired": "This account has been retired — sign in with the account it was migrated to.",
   "no_migration": "There is no migration in progress.",
   "not_confirmed": "Confirm it's you in this browser first. A confirmation lasts 10 minutes.",
+  "migrate_quota_exceeded": "The servers this migration brings over don't fit your quota. Ask an admin to raise it, then redeem the same code again before it expires.",
   "invalid_quota": "A quota must be a whole number from 0 to 2147483647. Leave it empty for unlimited.",
   "already_confirmed": "This migration has already been confirmed.",
   "invalid_target": "The migration target must be a different account.",