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_tokens.rs

@@ -0,0 +1,68 @@
+use std::sync::Arc;
+
+use domain::models::WatchEventSource;
+use domain::testing::InMemoryWebhookTokenRepository;
+use uuid::Uuid;
+
+use crate::integrations::{
+    commands::GenerateWebhookTokenCommand, generate_token, get_tokens,
+    queries::GetWebhookTokensQuery,
+};
+use crate::test_helpers::TestContextBuilder;
+
+#[tokio::test]
+async fn returns_empty_when_no_tokens() {
+    let tokens = InMemoryWebhookTokenRepository::new();
+    let ctx = TestContextBuilder::new()
+        .with_webhook_tokens(Arc::clone(&tokens) as _)
+        .build();
+
+    let result = get_tokens::execute(
+        &ctx,
+        GetWebhookTokensQuery {
+            user_id: Uuid::new_v4(),
+        },
+    )
+    .await
+    .unwrap();
+
+    assert!(result.is_empty());
+}
+
+#[tokio::test]
+async fn returns_tokens_after_generate() {
+    let tokens = InMemoryWebhookTokenRepository::new();
+    let ctx = TestContextBuilder::new()
+        .with_webhook_tokens(Arc::clone(&tokens) as _)
+        .build();
+
+    let user_id = Uuid::new_v4();
+
+    generate_token::execute(
+        &ctx,
+        GenerateWebhookTokenCommand {
+            user_id,
+            provider: WatchEventSource::Jellyfin,
+            label: None,
+        },
+    )
+    .await
+    .unwrap();
+
+    generate_token::execute(
+        &ctx,
+        GenerateWebhookTokenCommand {
+            user_id,
+            provider: WatchEventSource::Plex,
+            label: Some("living room".into()),
+        },
+    )
+    .await
+    .unwrap();
+
+    let result = get_tokens::execute(&ctx, GetWebhookTokensQuery { user_id })
+        .await
+        .unwrap();
+
+    assert_eq!(result.len(), 2);
+}