app: add core use cases (RegisterUser, CreateAlbum) with TDD

crates/application/tests/use_cases/organization/create_album.rs

@@ -0,0 +1,24 @@
+use std::sync::Arc;
+use application::testing::InMemoryAlbumRepository;
+use application::use_cases::CreateAlbum;
+use domain::errors::DomainError;
+use domain::value_objects::SystemId;
+
+#[tokio::test]
+async fn creates_album() {
+    let repo = Arc::new(InMemoryAlbumRepository::new());
+    let uc = CreateAlbum::new(repo);
+    let creator = SystemId::new();
+    let album = uc.execute("Vacation 2024", creator).await.unwrap();
+    assert_eq!(album.title, "Vacation 2024");
+    assert_eq!(album.creator_user_id, creator);
+    assert_eq!(album.asset_count(), 0);
+}
+
+#[tokio::test]
+async fn rejects_empty_title() {
+    let repo = Arc::new(InMemoryAlbumRepository::new());
+    let uc = CreateAlbum::new(repo);
+    let result = uc.execute("", SystemId::new()).await;
+    assert!(matches!(result, Err(DomainError::Validation(_))));
+}

crates/application/tests/use_cases/organization/mod.rs

@@ -0,0 +1 @@
+mod create_album;