refactor: move domain inline tests to separate files under tests/

Match the application crate convention: each source file references its
tests via #[cfg(test)] #[path = "tests/filename.rs"] mod tests; with
the test code in a sibling tests/ directory.

- events.rs       -> tests/events.rs
- value_objects.rs -> tests/value_objects.rs
- models/mod.rs   -> models/tests/mod.rs  (renamed from tests.rs)
- models/person.rs -> models/tests/person.rs
- models/goal.rs   -> models/tests/goal.rs
- models/watch_event.rs -> models/tests/watch_event.rs
- services/review_history.rs -> services/tests/review_history.rs

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

@@ -0,0 +1,55 @@
+use super::*;
+
+#[test]
+fn person_new() {
+    let ext = ExternalPersonId::new("tmdb:12345");
+    let pid = PersonId::from_external(&ext);
+    let p = Person::new(
+        pid,
+        ext,
+        "Keanu Reeves".into(),
+        Some("Acting".into()),
+        Some("/profiles/keanu.jpg".into()),
+    );
+    assert_eq!(p.name(), "Keanu Reeves");
+    assert_eq!(p.known_for_department(), Some("Acting"));
+    assert_eq!(p.profile_path(), Some("/profiles/keanu.jpg"));
+    assert_eq!(p.external_id().value(), "tmdb:12345");
+    assert_eq!(p.external_id().tmdb_id(), Some(12345));
+}
+
+#[test]
+fn person_id_from_external() {
+    let ext = ExternalPersonId::new("tmdb:99999");
+    let pid = PersonId::from_external(&ext);
+    // UUIDv5 is deterministic — just ensure it's a valid uuid
+    let _ = pid.value();
+}
+
+#[test]
+fn person_id_deterministic() {
+    let ext = ExternalPersonId::new("tmdb:42");
+    let a = PersonId::from_external(&ext);
+    let b = PersonId::from_external(&ext);
+    assert_eq!(a, b);
+}
+
+#[test]
+fn person_credits_default_empty() {
+    let ext = ExternalPersonId::new("tmdb:1");
+    let pid = PersonId::from_external(&ext);
+    let p = Person::new(pid, ext, "Test".into(), None, None);
+    let credits = PersonCredits {
+        person: p,
+        cast: vec![],
+        crew: vec![],
+    };
+    assert!(credits.cast.is_empty());
+    assert!(credits.crew.is_empty());
+}
+
+#[test]
+fn external_person_id_tmdb_id_none_for_other() {
+    let ext = ExternalPersonId::new("imdb:nm0000206");
+    assert_eq!(ext.tmdb_id(), None);
+}