add 400+ unit tests for domain and application layers

Extract ReviewLogger trait to decouple import/integrations
from diary::log_review (cross-module coupling smell).

Add in-memory fakes for all repository ports, enabling
isolated testing of every use case module without a database.

Coverage: domain+application 22% → 80%, 427 tests.

crates/application/src/import/list_profiles.rs

@@ -7,3 +7,7 @@ pub async fn execute(
 ) -> Result<Vec<ImportProfile>, DomainError> {
     ctx.repos.import_profile.list_for_user(user_id).await
 }
+
+#[cfg(test)]
+#[path = "tests/list_profiles.rs"]
+mod tests;