* test: add unit tests for ChatPersistenceRepository
Added ChatPersistenceRepositoryTest to verify the repository
correctly delegates to the ChatMessageDao and maps between
ChatMessage UI models and Room entity objects. Uses the
existing FakeChatMessageDao for reliable in-memory testing.
* test: fix ktlint issues in ChatPersistenceRepositoryTest
Formatted ChatPersistenceRepositoryTest to comply with standard
ktlint rules for the project.
* test: enhance ChatPersistenceRepositoryTest coverage
Added role and content assertions to `persistMessages_upsertsAllToDao`
and added a new `loadMessages_filtersBySessionId` test to verify
session isolation per PR feedback.
M57
992de56059