feat: domain mocks, TestContextBuilder, use case tests, factory pattern

- Add test-helpers feature to domain crate with in-memory mocks and panic stubs for all ports
- Add TestContextBuilder to application crate for zero-database test setup
- Add unit tests for log_review, register, login, add_to_watchlist, delete_review use cases
- Extract DatabaseAdapters factory and build_* helpers into presentation/src/factory.rs
- Refactor wire_dependencies() in main.rs to use factory module

crates/application/src/use_cases/login.rs

@@ -37,3 +37,92 @@ pub async fn execute(ctx: &AppContext, query: LoginQuery) -> Result<LoginResult,
         expires_at: generated.expires_at,
     })
 }
+
+#[cfg(test)]
+mod tests {
+    use std::sync::Arc;
+
+    use domain::models::UserRole;
+    use domain::testing::InMemoryUserRepository;
+
+    use crate::{
+        commands::RegisterCommand,
+        queries::LoginQuery,
+        test_helpers::TestContextBuilder,
+        use_cases::{login, register},
+    };
+
+    async fn setup_user(ctx: &crate::context::AppContext, email: &str, password: &str) {
+        register::execute(
+            ctx,
+            RegisterCommand {
+                email: email.to_string(),
+                username: "testuser".to_string(),
+                password: password.to_string(),
+                role: UserRole::Standard,
+            },
+        )
+        .await
+        .unwrap();
+    }
+
+    #[tokio::test]
+    async fn test_login_valid_credentials_returns_token() {
+        let users = InMemoryUserRepository::new();
+        let ctx = TestContextBuilder::new()
+            .with_users(Arc::clone(&users) as _)
+            .build();
+
+        setup_user(&ctx, "carol@example.com", "secret123").await;
+
+        let result = login::execute(
+            &ctx,
+            LoginQuery {
+                email: "carol@example.com".into(),
+                password: "secret123".into(),
+            },
+        )
+        .await
+        .unwrap();
+
+        assert!(!result.token.is_empty());
+        assert_eq!(result.email, "carol@example.com");
+    }
+
+    #[tokio::test]
+    async fn test_login_wrong_password_fails() {
+        let users = InMemoryUserRepository::new();
+        let ctx = TestContextBuilder::new()
+            .with_users(Arc::clone(&users) as _)
+            .build();
+
+        setup_user(&ctx, "dave@example.com", "correct_password").await;
+
+        let result = login::execute(
+            &ctx,
+            LoginQuery {
+                email: "dave@example.com".into(),
+                password: "wrong_password".into(),
+            },
+        )
+        .await;
+
+        assert!(result.is_err());
+    }
+
+    #[tokio::test]
+    async fn test_login_unknown_email_fails() {
+        let ctx = TestContextBuilder::new().build();
+
+        let result = login::execute(
+            &ctx,
+            LoginQuery {
+                email: "nobody@example.com".into(),
+                password: "anything".into(),
+            },
+        )
+        .await;
+
+        assert!(result.is_err());
+    }
+}