feat(tmdb): add TmdbMovieInfo DTO and get_movie_info

Symmetric to TmdbShowInfo / get_tv_show_info — gives the upcoming
sync_movie orchestrator a typed cache snapshot for the v2 movie
library index.

* TmdbMovieInfo(tmdb_id, imdb_id, title, release_year)
* parse_movie_info(details, external_ids) — pure builder, parses
  release_year from the first 4 chars of release_date (None on
  missing/empty/non-numeric)
* TMDBClient.get_movie_info(tmdb_id) — aggregates
  /movie/{id} + /movie/{id}/external_ids and feeds the parser

Tests cover happy path, missing/null/empty imdb_id, every
release_year edge (none/empty/short/non-numeric/missing key),
and the two required-field errors (id, title).

tests/infrastructure/api/test_tmdb_client.py

@@ -360,6 +360,46 @@ class TestGetTvShowInfo:
         assert info.seasons == ()
 
 
+class TestGetMovieInfo:
+    """``get_movie_info`` aggregates ``/movie/{id}`` + external_ids."""
+
+    @patch("alfred.infrastructure.api.tmdb.client.requests.get")
+    def test_happy_path(self, mock_get, client):
+        details = {
+            "id": 27205,
+            "title": "Inception",
+            "release_date": "2010-07-16",
+        }
+        external = {"imdb_id": "tt1375666"}
+        mock_get.side_effect = [
+            _ok_response(details),
+            _ok_response(external),
+        ]
+
+        info = client.get_movie_info(27205)
+
+        assert info.tmdb_id == 27205
+        assert info.imdb_id == "tt1375666"
+        assert info.title == "Inception"
+        assert info.release_year == 2010
+
+    @patch("alfred.infrastructure.api.tmdb.client.requests.get")
+    def test_missing_imdb_id_becomes_none(self, mock_get, client):
+        mock_get.side_effect = [
+            _ok_response(
+                {
+                    "id": 1,
+                    "title": "X",
+                    "release_date": "2024-01-01",
+                }
+            ),
+            _ok_response({}),
+        ]
+        info = client.get_movie_info(1)
+        assert info.imdb_id is None
+        assert info.release_year == 2024
+
+
 class TestIsConfigured:
     def test_true_when_complete(self, client):
         assert client.is_configured() is True