E5 S2: prioritise TMDB crew, and capture the TV showrunner

A live smoke against the real TMDB API showed two crew problems the mocked
tests missed: (1) a TV show's creator/showrunner lives in the payload's
top-level `created_by`, not the crew list, so it was dropped entirely; and
(2) TMDB's crew order is arbitrary — a TV show's per-episode Directors (dozens)
flooded the key-crew list and buried the show-level roles.

Fix: split the accepted crew jobs by media type — movies key on
Director/Writer/…; TV keys on Creator (from created_by) + the show-level
Executive Producer/Writer/Producer/Composer, deliberately excluding the
per-episode Director/Editor/DP noise. Stored crew is sorted by display
priority and capped, so the lead roles come first.

Verified live: Breaking Bad -> [Gilligan (Creator), Johnson (EP), … , Writer];
The Godfather -> [Coppola (Director), Puzo (Screenplay), …]. test_plex_tmdb
green (9).

backend/tests/test_plex_tmdb.py

@@ -44,6 +44,7 @@ TV_PAYLOAD = {
     "id": 1396,
     "vote_average": 9.0,
     "vote_count": 12000,
+    "created_by": [{"id": 66633, "name": "Vince Gilligan", "profile_path": "/vg.jpg"}],
     "keywords": {"results": [{"name": "drugs"}, {"name": "new mexico"}]},
     "aggregate_credits": {
         "cast": [{"id": 17419, "name": "Bryan Cranston"}],
@@ -102,9 +103,12 @@ def test_parse_tv_uses_aggregate_credits_and_no_money():
     d = tmdb.parse_tmdb(TV_PAYLOAD, "tv")
     assert d["budget"] is None and d["revenue"] is None  # TV has neither
     assert d["keywords"] == ["drugs", "new mexico"]  # from keywords.results
+    # The showrunner (created_by → Creator) leads; the aggregate-credits EP follows; the Sound person is
+    # filtered; TV jobs are read from jobs[0]. Crew is display-priority ordered (Creator before EP).
     assert d["crew"] == [
-        {"name": "Vince Gilligan", "job": "Executive Producer", "tmdb_id": 66633, "profile_path": None}
-    ]  # the Sound person is filtered; job read from jobs[0]
+        {"name": "Vince Gilligan", "job": "Creator", "tmdb_id": 66633, "profile_path": "/vg.jpg"},
+        {"name": "Vince Gilligan", "job": "Executive Producer", "tmdb_id": 66633, "profile_path": None},
+    ]
     assert d["tmdb_rating"] == 9.0
     assert ("Bryan Cranston", 17419) in {(p["name"], p["tmdb_id"]) for p in d["people"]}