refactor: drop server-seeded widget clock

The WidgetTimeProvider plumbed a server timestamp and the container's
timezone down to useWidgetNow so clock widgets would paint a real time in
the SSR HTML instead of "--:--". That traded a cosmetic first-paint win for
a wrong clock: the seeded timezone is the server's, so anyone whose timezone
differs from the container's saw an incorrect time for the whole hydration
window. Fixing that properly needs a client-set timezone cookie read during
RSC render, which is far more plumbing than the problem warrants.

Revert the clock to release/v2 behaviour ("--:--" until hydration) and drop
the provider, the @homarr/widgets/time export and their tests. The e2e clock
assertions now wait on hydration explicitly instead of the seeded paint.

Also restore the widget.beszel.getSystemStats persistence exclusion. #6289
added it deliberately to keep those large time-series payloads out of the
persisted cache, and this branch had removed it with no stated rationale.

Query-cache persistence and the background-refresh indicator are unchanged.

apps/nextjs/src/app/[locale]/boards/(content)/_client.tsx

@@ -9,7 +9,6 @@ import { useEditMode } from "@homarr/boards/edit-mode";
 import { getRepresentativeLayoutWidth } from "@homarr/boards/layout-preview";
 import { useI18n } from "@homarr/translation/client";
 import { FloatingTip } from "@homarr/ui";
-import { WidgetTimeProvider } from "@homarr/widgets/time";
 
 import { BoardAdvancedFocusProvider } from "~/components/board/advanced-focus/context";
 import { BoardEmptyState } from "~/components/board/board-empty-state";
@@ -40,13 +39,7 @@ const BoardSelectionGridProvider = ({ children }: PropsWithChildren) => (
   </GridEditorRegistryProvider>
 );
 
-export const ClientBoard = ({
-  initialTimestamp,
-  initialTimeZone,
-}: {
-  initialTimestamp: number;
-  initialTimeZone: string;
-}) => {
+export const ClientBoard = () => {
   const board = useRequiredBoard();
   const t = useI18n("board.landmark");
   const tPreview = useI18n("board.setting.section.layout.preview");
@@ -162,27 +155,23 @@ export const ClientBoard = ({
     </BoardSelectionGridProvider>
   );
 
+  if (representativeWidth === null) return content;
+
   return (
-    <WidgetTimeProvider initialTimestamp={initialTimestamp} initialTimeZone={initialTimeZone}>
-      {representativeWidth === null ? (
-        content
-      ) : (
-        <Stack align="center" gap="xs" p="md" mih="100%">
-          <Text size="xs" c="dimmed" fw={500}>
-            {tPreview("editorWidthLabel", { layoutName: currentLayout.name, width: representativeWidth })}
-          </Text>
-          <Paper
-            withBorder
-            shadow="sm"
-            radius="md"
-            w={`min(${representativeWidth}px, calc(100vw - 2rem))`}
-            mih="calc(100dvh - 8rem)"
-            style={{ overflow: "hidden" }}
-          >
-            {content}
-          </Paper>
-        </Stack>
-      )}
-    </WidgetTimeProvider>
+    <Stack align="center" gap="xs" p="md" mih="100%">
+      <Text size="xs" c="dimmed" fw={500}>
+        {tPreview("editorWidthLabel", { layoutName: currentLayout.name, width: representativeWidth })}
+      </Text>
+      <Paper
+        withBorder
+        shadow="sm"
+        radius="md"
+        w={`min(${representativeWidth}px, calc(100vw - 2rem))`}
+        mih="calc(100dvh - 8rem)"
+        style={{ overflow: "hidden" }}
+      >
+        {content}
+      </Paper>
+    </Stack>
   );
 };

apps/nextjs/src/app/[locale]/boards/(content)/_creator.tsx

@@ -96,10 +96,7 @@ export const createBoardContentPage = <TParams extends Record<string, unknown>>(
       return (
         <HydrationBoundary state={dehydrate(queryClient)}>
           <IntegrationProvider integrations={integrations}>
-            <ClientBoard
-              initialTimestamp={Date.now()}
-              initialTimeZone={Intl.DateTimeFormat().resolvedOptions().timeZone}
-            />
+            <ClientBoard />
           </IntegrationProvider>
         </HydrationBoundary>
       );