feat(plex): classify collection-strip source (franchise/imdb/tmdb/smart)

Derive a `source` bucket per collection from the already-synced title + smart
flag (no schema change, no re-sync): external list providers (IMDb/TMDb/TVDb/
Trakt) by leading token, Plex smart lists via the smart flag, everything else a
genuine "collection". Returned on each info-page collection strip so the client
can show/hide each type independently. Adds the stripSource labels (en/hu/de).

backend/app/routes/plex.py

@@ -684,6 +684,22 @@ def person_image(u: str, _: User = Depends(current_user)) -> Response:
     return _img_response(r.content, ct)
 
 
+# Known external list providers that seed Plex collections (via plextraktsync et al). A collection's
+# "source" buckets the info-page strips so the user can show/hide each type independently (e.g. hide
+# the noisy 'IMDb Popular'/'TMDb Trending' auto-lists but keep genuine franchise collections). Derived
+# from the already-synced title/smart — no schema change, no re-sync. Unknown providers stay "collection".
+_STRIP_PROVIDERS = ("imdb", "tmdb", "tvdb", "trakt")
+
+
+def _collection_source(col: PlexCollection) -> str:
+    first = (col.title or "").strip().split(" ", 1)[0].lower()
+    if first in _STRIP_PROVIDERS:
+        return first
+    if col.smart:
+        return "smart"
+    return "collection"
+
+
 def _collection_strips(db: Session, it: PlexItem, user_id: int) -> list[dict]:
     """The collections this movie belongs to, each with its member titles (playable cards) — the
     'Avatar Collection' strip on the info page. Pure local lookup (no Plex call)."""
@@ -714,7 +730,14 @@ def _collection_strips(db: Session, it: PlexItem, user_id: int) -> list[dict]:
                 PlexState.user_id == user_id, PlexState.item_id.in_(ids or [0])
             )
         }
-        out.append({"id": rk, "title": col.title, "items": [_movie_card(m, states.get(m.id)) for m in members]})
+        out.append(
+            {
+                "id": rk,
+                "title": col.title,
+                "source": _collection_source(col),
+                "items": [_movie_card(m, states.get(m.id)) for m in members],
+            }
+        )
     return out