Add a property-based test that proves MessageId survives serde and string roundtrips.
Acceptance criteria:
- Add
proptest coverage for MessageId
- Verify serde serialization/deserialization roundtrips
- Verify string parse/display roundtrips
- Keep the test narrow and deterministic
Add a property-based test that proves
MessageIdsurvives serde and string roundtrips.Acceptance criteria:
proptestcoverage forMessageId