Move external secrets behind auth broker

app/test/auth/auth_session_store_test.dart

@@ -22,13 +22,6 @@ void main() {
         tenantName: 'Hanmac',
         tenantSlug: 'hanmac',
       ),
-      orgContextCredential: OrgContextCredential(
-        baseUrl: 'https://sadmin.hmac.kr',
-        tenantSlug: 'hanmac-family',
-        keyId: 'session-key-id',
-        keySecret: 'session-key-secret',
-        expiresAt: DateTime.parse('2099-07-02T13:00:00Z'),
-      ),
     );
 
     await store.save(response);
@@ -36,8 +29,6 @@ void main() {
 
     expect(loaded?.token, 'session-token');
     expect(loaded?.user.name, 'User One');
-    expect(loaded?.orgContextCredential?.keyId, 'session-key-id');
-    expect(loaded?.orgContextCredential?.keySecret, 'session-key-secret');
 
     await store.clear();
     expect(await store.load(), isNull);