No test covers the encryption round-trip; existing context test cannot catch the bug #56

File: core/csharp/MicroZen.Api.Test/Context/MicroZenContextTests.cs

What this is: The reference test persists an Organization and reads it back.

Problem: It only checks unencrypted fields of an entity that has no [EncryptColumn] properties, so the inverted-encryption bug (see the "Encryption is inverted" Must Fix issue) sails through green. No test ever round-trips an OAuth2ClientCredentials secret through the converter.

Fix: Add a test that saves an OAuth2ClientCredentials, reads the raw stored value, and asserts the secret is NOT readable plaintext while the name IS — this fails today and would have caught the inverted-encryption bug.

If we skip it: The most dangerous bug stays invisible to CI.