feat(plex): port the saved-views (personal views) UI to Plex (frontend)

Plex now has the same personal-views system as the feed — the rail header icon
opens the quick-pick popover, the rail title opens the manager modal (list /
create / rename / delete / reorder / set-default / apply), and the active view
leads the chip row with a "modified" dot.

One SavedViewsProvider serves both modules: it switches `source` (feed ⟷ plex)
by the active page (both filter providers are global, so it reads whichever the
page owns) and runs the same logic on per-source wiring — the live filters,
apply, a stable signature (feed filtersToParams / plex plexFiltersSignature),
coercion (asFilters / coercePlexFilters), and what to strip on save. Moved below
PlexProvider in the tree so it can read plex state; resets sticky/modal on a
source switch. The shared popover/modal/chip are unchanged; the modal describes
a plex view's captured filters via a pure buildPlexActiveFilters (extracted from
usePlexActiveFilters — no duplication). api.savedViews/createView take a source;
`SavedView.filters` is now an opaque blob. New coercePlexFilters/plexFilters-
Signature (also dedups PlexProvider's collection migration). Empty-state copy
genericised (no longer says "feed"). A Plex view captures the rail filters (not
watch-state/sort/scope).

Verified end-to-end on localdev: create/apply/preview/default/delete on plex,
feed views stay separate + unregressed (402 vitest), no console errors.

frontend/src/components/PersonalViewsModal.tsx

@@ -16,10 +16,11 @@ import {
   verticalListSortingStrategy,
 } from "@dnd-kit/sortable";
 import { CSS } from "@dnd-kit/utilities";
-import type { SavedView } from "../lib/api";
+import { coercePlexFilters, type FeedFilters, type SavedView } from "../lib/api";
 import Modal from "./Modal";
 import { useSavedViews, asFilters } from "./SavedViewsProvider";
 import { useActiveFilters } from "../lib/useActiveFilters";
+import { buildPlexActiveFilters } from "./usePlexActiveFilters";
 
 // Master–detail manager for saved ("personal") views: the left column lists the views (drag to
 // reorder) plus a "save the current filters" input; the right column shows the selected view's name,
@@ -72,19 +73,38 @@ function ViewRow({
 
 export default function PersonalViewsModal() {
   const { t } = useTranslation();
-  const { views, activeViewId, apply, create, rename, toggleDefault, remove, reorder, closeModal } =
-    useSavedViews();
+  const {
+    source,
+    views,
+    activeViewId,
+    apply,
+    create,
+    rename,
+    toggleDefault,
+    remove,
+    reorder,
+    closeModal,
+  } = useSavedViews();
   const sensors = useSensors(useSensor(PointerSensor, { activationConstraint: { distance: 4 } }));
 
   const [selectedId, setSelectedId] = useState<number | null>(activeViewId ?? views[0]?.id ?? null);
   const selected = views.find((v) => v.id === selectedId) ?? null;
   const [draftName, setDraftName] = useState("");
 
-  // The selected view's captured filters, as the same human labels the toolbar chip row shows.
-  const captured = useActiveFilters(
-    selected ? asFilters(selected.filters) : ({ tags: [], channelIds: [] } as never),
-    () => {},
+  // The selected view's captured filters, as the same human labels its module's chip row shows. The
+  // feed hook runs unconditionally (fed empty filters off-feed); Plex uses the pure builder (no-op
+  // removes — this is display-only). A plex view captures its rail filters, not the watch-state.
+  const noop = () => {};
+  const feedCaptured = useActiveFilters(
+    source === "feed" && selected
+      ? asFilters(selected.filters as unknown as FeedFilters)
+      : ({ tags: [], channelIds: [] } as never),
+    noop,
   );
+  const captured =
+    source === "plex" && selected
+      ? buildPlexActiveFilters(coercePlexFilters(selected.filters), "all", noop, noop, t)
+      : feedCaptured;
 
   async function onDragEnd(e: DragEndEvent) {
     const { active, over } = e;