fix(e5): deep-review round — combobox Enter, parse_person collision, enrich hardening + coverage

Full-epic /deep-review (11 finders + 12 adversarial verifiers) surfaced no HIGH; every
mechanism finding calibrated to LOW on verification. Fix all 13:

Correctness / reliability:
- Combobox: Enter now commits the VISUALLY highlighted row (highlightIndex ?? activeIndex),
  not the bare keyboard activeIndex — so arrow-then-hover-then-Enter no longer toggles a
  different option than the one painted, and hover-with-no-arrow is no longer a silent no-op.
- parse_person: dedup the known_for pool by (id, media_type), not the bare id — TMDB movie
  and tv id spaces are independent, so a same-id movie+show pair is two distinct credits
  (matches the collision-safe key the rest of the module already uses).
- person-enrich: a per-person in-flight + 60s cooldown guard (people._should_schedule_enrich)
  dedups concurrent opens and rate-limits re-triggering while TMDB is degraded (a transient
  TmdbError leaves the watermark NULL), so bursts can't pile 8s tasks onto the shared threadpool.
- PlexInfo compact()/money(): format with i18n.language (keeping currency USD) instead of a
  hardcoded en/en-US, matching the app's Intl convention.
- delete the dead `plex.filter.add` i18n key (both locales) — the +Add button that used it is gone.

Reuse:
- _continue_watching reuses rollup.agg_subquery(include_resumed=True) + query.apply_show_state_filter
  instead of a third hand-inlined copy of the per-show rollup + in_progress predicate, so the
  Discover rail can't drift from the grid's definition.

Test coverage (the gaps a regression would ship through):
- resolve_library_guids scope-exclusion (a credit in a non-scoped/disabled library is dropped)
  + the []-vs-None distinction; parse_person cross-media-id retention; enrich_person transient
  (NULL watermark) and 404 (stamp) branches; _enrich_person_bg body (fresh session close/rollback,
  None-guard) + the cooldown dedup; continue_watching fully-watched-show exclusion; Combobox
  Enter-commits-highlighted + async/controlled-query mode; PopoverItem aria-checked contract;
  RatingsRow missing-IMDb + imdb==audience branches.

Backend lane 413→420, FE vitest 351→357; all gates green. No migration.

backend/app/plex/rollup.py

@@ -42,27 +42,32 @@ def rollup(cards: list[dict]) -> dict:
     }
 
 
-def agg_subquery(db: Session, user_id: int):
+def agg_subquery(db: Session, user_id: int, include_resumed: bool = False):
     """Per-show episode counts for a user: total, watched, in-progress. Reused to (a) filter the show
-    grid by aggregate watch-state and (b) compute each card's badge."""
+    grid by aggregate watch-state, (b) compute each card's badge, and (c) drive the Discover
+    continue-watching rail. `include_resumed` adds `resumed_at` = max(progress_updated_at) across the
+    show's episodes, so the rail can order shows by how recently they were last progressed."""
     ps = aliased(PlexState)
-    return (
-        select(
-            PlexItem.show_id.label("show_id"),
-            func.count(PlexItem.id).label("total"),
-            func.count(case((ps.status == "watched", 1))).label("watched"),
-            func.count(
-                case(
-                    (
-                        and_(
-                            ps.position_seconds > 0,
-                            or_(ps.status.is_(None), ps.status != "watched"),
-                        ),
-                        1,
-                    )
+    cols = [
+        PlexItem.show_id.label("show_id"),
+        func.count(PlexItem.id).label("total"),
+        func.count(case((ps.status == "watched", 1))).label("watched"),
+        func.count(
+            case(
+                (
+                    and_(
+                        ps.position_seconds > 0,
+                        or_(ps.status.is_(None), ps.status != "watched"),
+                    ),
+                    1,
                 )
-            ).label("inprog"),
-        )
+            )
+        ).label("inprog"),
+    ]
+    if include_resumed:
+        cols.append(func.max(ps.progress_updated_at).label("resumed_at"))
+    return (
+        select(*cols)
         .outerjoin(ps, and_(ps.item_id == PlexItem.id, ps.user_id == user_id))
         .where(PlexItem.kind == "episode", PlexItem.show_id.isnot(None))
         .group_by(PlexItem.show_id)