fix(plex): the rails' Restart comes from the one rollup; plain text decodes whole entity names only

Both Continue-watching rails built a show's card state inline; they now take it from rollup.show_state, so a show part watched with nothing to resume offers Play alone there too. A named reference counts only when its whole name is an HTML5 entity: html.unescape still decoded the legacy "&not" inside "&notice;". Tests cover the grid's in-progress-but-not-resumable case through its SQL and both rails.

backend/app/plex/rollup.py

@@ -107,7 +107,7 @@ def state_map(db: Session, user_id: int, show_ids: list[int]) -> dict[int, ShowS
 
 def item_state_map(db: Session, user_id: int, item_ids: list[int]) -> dict[int, PlexState]:
     """A user's PlexState rows for a set of leaf items (movies or episodes), keyed by item_id — the
-    leaf analogue of `state_map` (which rolls a show's episodes up to a status string). One batched
+    leaf analogue of `state_map` (which rolls a show's episodes up to a `ShowState`). One batched
     fetch, so the caller serializes cards without a per-card query. Empty in → empty dict (no `IN ()`)."""
     if not item_ids:
         return {}