fix(smartling): use oauthCallback to fix broken OAuth authentication [AIS-82] (#11049)

* fix(smartling): use oauthCallback to fix id_token not present in TokenSet

Smartling's SSO returns only access_token and refresh_token — no id_token.
client.callback() calls validateIdToken() after the code exchange and throws
"id_token not present in TokenSet" when id_token is absent. client.oauthCallback()
performs the same authorization_code grant but skips id_token validation entirely,
which is correct here since the app only ever uses access_token and refresh_token.

Confirmed broken in prod via CloudWatch: sls-apps-smartling-prd-app logging
"Smartling OAuth failed with message: id_token not present in TokenSet" on every
auth attempt.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* test(smartling): update mock to use oauthCallback

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: tylerwashington888

apps/smartling/lambda/src/index.spec.ts

@@ -27,7 +27,7 @@ class Client {
     return { code: '1234' };
   }
 
-  async callback() {
+  async oauthCallback() {
     return {
       access_token: 'access-123',
       refresh_token: 'refresh_token-123',

apps/smartling/lambda/src/index.ts

@@ -51,7 +51,7 @@ export function makeApp(fetchFn: any, issuer: any) {
 
     try {
       const params = client.callbackParams(req);
-      const data = await client.callback('', params);
+      const data = await client.oauthCallback('', params);
 
       res.redirect(
         `/frontend/index.html?access_token=${data.access_token}&refresh_token=${data.refresh_token}`