chore(auth): add error logging for saml-idp silent failures (#26484)
* chore(auth): add error logging for saml-idp silent failures
* chore(auth): add warn-level logging for saml-idp silent failures
* chore(auth): change 'No user found' log to warn level
* chore(auth): add warn-level logging for silent auth failures
- saml-idp authorize: credentials, code, token, userInfo, user lookup
- callbacks:signIn: account type, email, name, catch-all
- callbacks:jwt: unknown account type (info → warn)
- saml:profile: missing email from IdP
- getServerSession: user not found for valid token