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/tests/test_plex_discover.py

@@ -140,6 +140,30 @@ def test_continue_watching_null_status_in_hidden_out(db, monkeypatch):
     assert "mh" not in ids  # hidden is excluded
 
 
+def test_continue_watching_excludes_fully_watched_show(db, monkeypatch):
+    # A show whose every episode is watched is DONE, not in-progress: the `watched < total` guard must
+    # keep it off the Continue-watching rail (a bare `watched > 0` would wrongly resurface it).
+    lib_s = PlexLibrary(plex_key="2", title="Shows", kind="show", enabled=True)
+    db.add(lib_s)
+    db.flush()
+    sh = PlexShow(rating_key="shw", library_id=lib_s.id, title="All Watched", child_count=1)
+    db.add(sh)
+    db.flush()
+    ep = PlexItem(rating_key="shwe1", library_id=lib_s.id, kind="episode", title="E1",
+                  show_id=sh.id, season_number=1, episode_number=1)
+    db.add(ep)
+    db.flush()
+    user = User(email="fullywatched@example.com")
+    db.add(user)
+    db.flush()
+    db.add(PlexState(user_id=user.id, item_id=ep.id, status="watched", position_seconds=0,
+                     progress_updated_at=NOW))
+    db.commit()
+
+    ids = _ids(_get(db, user, monkeypatch, "/api/plex/discover?scope=show").json()["continue_watching"])
+    assert "shw" not in ids  # fully watched → excluded from continue-watching
+
+
 def test_because_you_watched_resolves_in_library_recs(db, monkeypatch):
     user = _seed(db)
     d = _get(db, user, monkeypatch, "/api/plex/discover?scope=both").json()