Follow-ups: reference reorder, detach service_id, named-dashboard widgets

Three reusable-widget follow-up fixes:

1. Reference sort_order independently reorderable. Reordering a
   referenced widget now updates the widget_references.sort_order (per-
   dashboard), not the shared widget instance sort_order. New backend
   update_widget_reference method + PUT /api/widgets/references/{id}
   endpoint. Frontend moveInstance checks _ref_id to choose the right
   mutation (updateRef for references, saveWidget for owned).

2. Detach preserves service_id. detach_widget_reference now copies the
   original widget's service_id into the clone, so service-bound widgets
   (Grafana chart, Jellyfin activity) continue to render after detach.

3. Named dashboards support widget references. NamedDashboardPage
   fetches useWidgetReferences('named:<slug>') and renders them via
   WidgetInstanceCard alongside pinned links. 'Edit widgets' button
   opens WidgetConfigDialog with dashboardScope='named:<slug>'.

Also: removed useMemo on combinedWidgets in WidgetConfigDialog to fix
a react-hooks/preserve-manual-memoization lint error (the React Compiler
ESLint plugin couldn't verify the spread+sort memoization).

283 backend tests pass (+1 update_reference test); 128 frontend tests
pass; ruff clean; 0 lint errors.

backend/tests/test_widgets.py

@@ -730,6 +730,7 @@ async def test_jellyfin_activity_shows_all_sessions():
 # Widget references (live-link widgets across dashboards)
 # ---------------------------------------------------------------------------
 
+
 @pytest.fixture
 def widget_ref_client(monkeypatch):
     """TestClient with an isolated SettingsStore + encryption key."""
@@ -770,21 +771,26 @@ def test_widget_reference_lifecycle(widget_ref_client):
         },
     )
     service = store.list_services("grafana")[0]
-    widget = store.upsert_widget({
-        "service_id": service["id"],
-        "widget_kind": "chart",
-        "title": "CPU IOWait",
-        "config": {"query": "rate(cpu[5m])", "datasource_uid": "prometheus"},
-        "enabled": True,
-        "sort_order": 0,
-    })
+    widget = store.upsert_widget(
+        {
+            "service_id": service["id"],
+            "widget_kind": "chart",
+            "title": "CPU IOWait",
+            "config": {"query": "rate(cpu[5m])", "datasource_uid": "prometheus"},
+            "enabled": True,
+            "sort_order": 0,
+        }
+    )
 
     # Reference it on "main" dashboard.
-    resp = client.post("/api/widgets/references", json={
-        "dashboard_scope": "main",
-        "widget_id": widget["id"],
-        "sort_order": 5,
-    })
+    resp = client.post(
+        "/api/widgets/references",
+        json={
+            "dashboard_scope": "main",
+            "widget_id": widget["id"],
+            "sort_order": 5,
+        },
+    )
     assert resp.status_code == 201
     ref = resp.json()
     assert ref["dashboard_scope"] == "main"
@@ -823,20 +829,25 @@ def test_widget_reference_detach(widget_ref_client):
         },
     )
     service = store.list_services("grafana")[0]
-    widget = store.upsert_widget({
-        "service_id": service["id"],
-        "widget_kind": "chart",
-        "title": "Memory",
-        "config": {"query": "mem", "datasource_uid": "prometheus"},
-        "enabled": True,
-        "sort_order": 0,
-    })
+    widget = store.upsert_widget(
+        {
+            "service_id": service["id"],
+            "widget_kind": "chart",
+            "title": "Memory",
+            "config": {"query": "mem", "datasource_uid": "prometheus"},
+            "enabled": True,
+            "sort_order": 0,
+        }
+    )
 
     # Reference on "main".
-    resp = client.post("/api/widgets/references", json={
-        "dashboard_scope": "main",
-        "widget_id": widget["id"],
-    })
+    resp = client.post(
+        "/api/widgets/references",
+        json={
+            "dashboard_scope": "main",
+            "widget_id": widget["id"],
+        },
+    )
     ref_id = resp.json()["id"]
 
     # Detach.
@@ -845,7 +856,7 @@ def test_widget_reference_detach(widget_ref_client):
     cloned = resp.json()
     assert cloned["title"] == "Memory"
     assert cloned["widget_kind"] == "chart"
-    assert cloned["service_id"] is None  # dashboard-scoped clone
+    assert cloned["service_id"] == service["id"]  # Fix 2: preserves service binding
     assert cloned["config"]["query"] == "mem"
     assert cloned["id"] != widget["id"]  # new independent widget
 
@@ -854,3 +865,62 @@ def test_widget_reference_detach(widget_ref_client):
     assert len(refs) == 0
     # Original still exists.
     assert store.get_widget(widget["id"]) is not None
+
+
+def test_widget_reference_update_sort_order(widget_ref_client):
+    """PUT /references/{id} updates only the reference's sort_order (Fix 1)."""
+    client, store = widget_ref_client
+
+    widget_a = store.upsert_widget(
+        {
+            "service_id": None,
+            "widget_kind": "static",
+            "title": "A",
+            "config": {"text": "a"},
+            "enabled": True,
+            "sort_order": 0,
+        }
+    )
+    widget_b = store.upsert_widget(
+        {
+            "service_id": None,
+            "widget_kind": "static",
+            "title": "B",
+            "config": {"text": "b"},
+            "enabled": True,
+            "sort_order": 1,
+        }
+    )
+
+    # Two references on the same dashboard scope.
+    resp = client.post(
+        "/api/widgets/references",
+        json={
+            "dashboard_scope": "named:test",
+            "widget_id": widget_a["id"],
+            "sort_order": 0,
+        },
+    )
+    ref_a = resp.json()
+    resp = client.post(
+        "/api/widgets/references",
+        json={
+            "dashboard_scope": "named:test",
+            "widget_id": widget_b["id"],
+            "sort_order": 1,
+        },
+    )
+    ref_b = resp.json()
+
+    # Swap sort orders via PUT (per-dashboard reorder).
+    resp = client.put(f"/api/widgets/references/{ref_a['id']}?sort_order=1")
+    assert resp.status_code == 200
+    assert resp.json()["sort_order"] == 1
+
+    resp = client.put(f"/api/widgets/references/{ref_b['id']}?sort_order=0")
+    assert resp.status_code == 200
+    assert resp.json()["sort_order"] == 0
+
+    # Widget instances themselves are unchanged.
+    assert store.get_widget(widget_a["id"])["sort_order"] == 0
+    assert store.get_widget(widget_b["id"])["sort_order"] == 1