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/integrations/tests/get_queue.rs

@@ -0,0 +1,56 @@
+use std::sync::Arc;
+
+use chrono::Utc;
+use domain::models::{WatchEvent, WatchEventSource};
+use domain::ports::WatchEventRepository;
+use domain::testing::InMemoryWatchEventRepository;
+use domain::value_objects::UserId;
+use uuid::Uuid;
+
+use crate::integrations::{get_queue, queries::GetWatchQueueQuery};
+use crate::test_helpers::TestContextBuilder;
+
+#[tokio::test]
+async fn returns_empty_when_no_events() {
+    let events = InMemoryWatchEventRepository::new();
+    let ctx = TestContextBuilder::new()
+        .with_watch_events(Arc::clone(&events) as _)
+        .build();
+
+    let result = get_queue::execute(
+        &ctx,
+        GetWatchQueueQuery {
+            user_id: Uuid::new_v4(),
+        },
+    )
+    .await
+    .unwrap();
+
+    assert!(result.is_empty());
+}
+
+#[tokio::test]
+async fn returns_pending_events() {
+    let events = InMemoryWatchEventRepository::new();
+    let ctx = TestContextBuilder::new()
+        .with_watch_events(Arc::clone(&events) as _)
+        .build();
+
+    let user_id = Uuid::new_v4();
+    let event = WatchEvent::new(
+        UserId::from_uuid(user_id),
+        "Blade Runner 2049".into(),
+        Some(2017),
+        None,
+        WatchEventSource::Jellyfin,
+        Utc::now().naive_utc(),
+        None,
+    );
+    events.save(&event).await.unwrap();
+
+    let result = get_queue::execute(&ctx, GetWatchQueueQuery { user_id })
+        .await
+        .unwrap();
+
+    assert_eq!(result.len(), 1);
+}