domain crate code quality cleanup

strip all comments, extract tests to tests/ dirs,
remove #[allow(clippy::...)], extract magic numbers to
constants, refactor schedule engine private methods to
use param structs, add Default impls, clippy.toml for
persistence constructors

crates/domain/src/models/tests/library.rs

@@ -0,0 +1,122 @@
+use super::*;
+
+#[test]
+fn library_item_new_generates_composite_id() {
+    let item = LibraryItem::new("jellyfin", "abc123", "Test Movie", ContentType::Movie, 7200, "2026-03-19T00:00:00Z");
+    assert_eq!(item.id(), "jellyfin::abc123");
+    assert_eq!(item.provider_id(), "jellyfin");
+    assert_eq!(item.external_id(), "abc123");
+}
+
+#[test]
+fn library_item_new_defaults_optional_fields() {
+    let item = LibraryItem::new("jf", "1", "Movie", ContentType::Movie, 3600, "2026-01-01");
+    assert!(item.series_name().is_none());
+    assert!(item.season_number().is_none());
+    assert!(item.genres().is_empty());
+    assert!(item.tags().is_empty());
+    assert!(item.collection_id().is_none());
+    assert!(item.thumbnail_url().is_none());
+}
+
+#[test]
+fn library_item_from_persistence_all_fields() {
+    let item = LibraryItem::from_persistence(
+        "jf::abc".into(),
+        "jf".into(),
+        "abc".into(),
+        "Breaking Bad S01E01".into(),
+        ContentType::Episode,
+        2700,
+        Some("Breaking Bad".into()),
+        Some(1),
+        Some(1),
+        Some(2008),
+        vec!["Drama".into()],
+        vec!["tv".into()],
+        Some("col-1".into()),
+        Some("TV Shows".into()),
+        Some("tvshows".into()),
+        Some("http://thumb.jpg".into()),
+        "2026-03-19T00:00:00Z".into(),
+    );
+    assert_eq!(item.series_name(), Some("Breaking Bad"));
+    assert_eq!(item.season_number(), Some(1));
+    assert_eq!(item.year(), Some(2008));
+    assert_eq!(item.collection_name(), Some("TV Shows"));
+}
+
+#[test]
+fn library_collection_new_and_getters() {
+    let col = LibraryCollection::new("col-1", "Movies");
+    assert_eq!(col.id(), "col-1");
+    assert_eq!(col.name(), "Movies");
+    assert!(col.collection_type().is_none());
+}
+
+#[test]
+fn library_collection_from_persistence() {
+    let col = LibraryCollection::from_persistence(
+        "col-2".into(),
+        "TV Shows".into(),
+        Some("tvshows".into()),
+    );
+    assert_eq!(col.collection_type(), Some("tvshows"));
+}
+
+#[test]
+fn sync_result_success() {
+    let r = LibrarySyncResult::new("jellyfin", 150, 1200);
+    assert_eq!(r.provider_id(), "jellyfin");
+    assert_eq!(r.items_found(), 150);
+    assert_eq!(r.duration_ms(), 1200);
+    assert!(r.error().is_none());
+}
+
+#[test]
+fn sync_result_with_error() {
+    let r = LibrarySyncResult::with_error("jellyfin", 500, "connection refused");
+    assert_eq!(r.items_found(), 0);
+    assert_eq!(r.error(), Some("connection refused"));
+}
+
+#[test]
+fn sync_log_entry_new_defaults() {
+    let entry = LibrarySyncLogEntry::new(1, "jellyfin", "2026-03-19T00:00:00Z");
+    assert_eq!(entry.id(), 1);
+    assert_eq!(entry.status(), SYNC_STATUS_RUNNING);
+    assert_eq!(entry.items_found(), 0);
+    assert!(entry.finished_at().is_none());
+    assert!(entry.error_msg().is_none());
+}
+
+#[test]
+fn show_summary_getters() {
+    let show = ShowSummary::from_persistence(
+        "Breaking Bad".into(),
+        62,
+        5,
+        Some("http://thumb.jpg".into()),
+        vec!["Drama".into(), "Crime".into()],
+    );
+    assert_eq!(show.series_name(), "Breaking Bad");
+    assert_eq!(show.episode_count(), 62);
+    assert_eq!(show.season_count(), 5);
+    assert_eq!(show.genres().len(), 2);
+}
+
+#[test]
+fn season_summary_getters() {
+    let season = SeasonSummary::from_persistence(1, 7, Some("http://s1.jpg".into()));
+    assert_eq!(season.season_number(), 1);
+    assert_eq!(season.episode_count(), 7);
+    assert_eq!(season.thumbnail_url(), Some("http://s1.jpg"));
+}
+
+#[test]
+fn season_summary_new_defaults() {
+    let season = SeasonSummary::new(3, 13);
+    assert_eq!(season.season_number(), 3);
+    assert_eq!(season.episode_count(), 13);
+    assert!(season.thumbnail_url().is_none());
+}