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/tmdb.py

@@ -434,13 +434,16 @@ def parse_person(payload: dict) -> dict:
     """TMDB /person/{id} (+combined_credits) → the persisted bio fields. `known_for` = the person's
     most-popular movie/tv credits (deduped by id), top `_KNOWN_FOR_MAX`, resolved to library later."""
     credits = (payload.get("combined_credits") or {}).get("cast") or []
-    seen: set[int] = set()
+    # Dedup on (id, media_type), not the bare id: TMDB movie ids and tv ids are independent sequences
+    # (id 603 can be both a movie and a show — see resolve_library_guids), so a same-id movie+show pair
+    # is two distinct credits and both must survive.
+    seen: set[tuple[int, str]] = set()
     known: list[dict] = []
     for c in sorted(credits, key=lambda c: c.get("popularity") or 0, reverse=True):
         tid, mt = c.get("id"), c.get("media_type")
-        if not tid or mt not in ("movie", "tv") or tid in seen:
+        if not tid or mt not in ("movie", "tv") or (tid, mt) in seen:
             continue
-        seen.add(tid)
+        seen.add((tid, mt))
         known.append({"tmdb_id": tid, "media_type": mt, "title": c.get("title") or c.get("name")})
         if len(known) >= _KNOWN_FOR_MAX:
             break