feat(jellyseer): sortable/filterable requests table on the Requests tab

Replace the static "recent requests" list with a proper table of all Jellyseerr
requests, sorted by date added (newest first by default) with standard sorting
and filtering.

Backend:
- JellyseerrClient.requests(max_count=500): paginated GET /api/v1/request
  (sort=added), mapped with type (movie/tv), status, media_status, and
  created_at labels. Returns up to 500 so the table can sort/filter client-side.
- fetch_jellyseer_requests(service) reuses the per-service cached client
  (shared with the stats widgets).
- new GET /api/jellyseerr/requests endpoint.

Frontend:
- JellyseerRequestsTable: TanStack Table (sorting via getSortedRowModel,
  pagination via getPaginationRowModel) reusing the Table primitives +
  TablePagination. Columns: Name / Type / Status / Media / Requested, all
  sortable; default sort Requested desc. A search box filters by name and a
  status dropdown defaults to "Open" (pending+approved+processing) with
  All/Pending/Approved/Declined options. (The shared DataTable is deliberately
  visibility-only, so this is a dedicated sortable table.)
- RequestsTab renders the stats grid + the new table (the compact recent list
  stays on the Requests overview widget).
- useJellyseerRequests hook + fetchJellyseerRequests API client.

Tests: client requests() mapping + single-page stop; fetch helper not-configured;
RequestsTab test mocks both hooks. 404/404 backend + 184/184 frontend pass;
build (tsc -b && vite build) + ESLint clean.

backend/tests/test_jellyseerr_stats.py

@@ -115,3 +115,49 @@ def test_stat_widget_unknown_stat_returns_error():
     with patch("media_library_viewer_api.widgets.sources.get_stats_provider", return_value=provider):
         data = asyncio.run(src.fetch(_service(), "stat", {"stat": "nope"}))
     assert "error" in data
+
+
+def test_jellyseer_client_requests_maps_fields():
+    """requests() paginates /request and maps type/status/media_status enums."""
+    from media_library_viewer_api.clients.jellyseerr import JellyseerrClient
+
+    c = JellyseerrClient("https://js.example.com", "key")
+    c.session = MagicMock()
+    resp = MagicMock()
+    resp.raise_for_status.return_value = None
+    resp.status_code = 200
+    resp.text = ""
+    resp.json.return_value = {
+        "results": [
+            {
+                "id": 7,
+                "type": 1,
+                "title": "Inception",
+                "status": 1,
+                "media": {"status": 5},
+                "createdAt": 1_700_000_000,
+            }
+        ]
+    }
+    c.session.get.return_value = resp
+
+    out = c.requests(500)
+
+    assert len(out) == 1
+    r = out[0]
+    assert r["id"] == 7
+    assert r["type"] == "movie"  # 1 -> movie
+    assert r["name"] == "Inception"
+    assert r["status"] == "pending"  # 1 -> pending
+    assert r["media_status"] == "available"  # 5 -> available
+    assert r["created_at"] == 1_700_000_000
+    # Single short page -> no second fetch.
+    assert c.session.get.call_count == 1
+
+
+def test_fetch_jellyseer_requests_not_configured_returns_empty():
+    """No jellyseerr config -> empty list (tab shows 'No requests')."""
+    from media_library_viewer_api.widgets.jellyseerr_stats import fetch_jellyseer_requests
+
+    service = ServiceRecord(id="s", service_type="jellyfin", name="JF", config={}, secrets={})
+    assert fetch_jellyseer_requests(service) == []