Use statusCodes.notFound instead of the magic 404

SonarCloud S109 on the ApiError 404 handling. Use the existing shared
statusCodes constant rather than a bare literal.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: timabell

src/server/routes/certificatesOfCompliance/certificates-of-compliance.service.js

@@ -1,5 +1,6 @@
 import { config } from '#config/config.js'
 import { ApiError } from '#services/apiBaseClient/api-error.js'
+import { statusCodes } from '#server/common/constants/status-codes.js'
 import { createAccountApiService } from '#services/account-api.service.js'
 import { format, isDate, parseISO } from 'date-fns'
 import { createWasteObligationsApiService } from '#services/waste-obligations-api.service.js'
@@ -523,7 +524,7 @@ async function fetchSubmitterPhoneNumber(accountApi, audit, traceId) {
     const details = await accountApi.getAccountDetailsById(userId, traceId)
     return details.telephone ?? null
   } catch (err) {
-    if (err instanceof ApiError && err.status === 404) {
+    if (err instanceof ApiError && err.status === statusCodes.notFound) {
       return null
     }
     throw err