feat: add shimmer bar when dashboard is refetching after filter change

Shows a thin animated orange bar below the filter bar while SWR
revalidates, so users know their filter was applied. Hidden on
initial load where the skeleton already provides feedback.

app/sites/[id]/page.tsx

@@ -237,7 +237,7 @@ export default function SiteDashboardPage() {
   // Single dashboard request replaces focused hooks (overview, pages, locations,
   // devices, referrers, goals). The backend runs all queries in parallel
   // and caches the result in Redis for efficient data loading.
-  const { data: dashboard, isLoading: dashboardLoading, error: dashboardError } = useDashboard(siteId, dateRange.start, dateRange.end, interval, filtersParam || undefined)
+  const { data: dashboard, isLoading: dashboardLoading, isValidating: dashboardValidating, error: dashboardError } = useDashboard(siteId, dateRange.start, dateRange.end, interval, filtersParam || undefined)
   const { data: realtimeData } = useRealtime(siteId)
   const { data: prevStats } = useStats(siteId, prevRange.start, prevRange.end)
   const { data: prevDailyStats } = useDailyStats(siteId, prevRange.start, prevRange.end, interval)
@@ -531,6 +531,13 @@ export default function SiteDashboardPage() {
         <FilterBar filters={filters} onRemove={handleRemoveFilter} onClear={handleClearFilters} />
       </div>
 
+      {/* Refetch indicator — visible when SWR is revalidating with stale data on screen */}
+      {dashboardValidating && !dashboardLoading && (
+        <div className="h-0.5 w-full rounded-full bg-neutral-100 dark:bg-neutral-800 overflow-hidden mb-2">
+          <div className="h-full w-1/3 rounded-full bg-brand-orange animate-[shimmer_1.2s_ease-in-out_infinite]" />
+        </div>
+      )}
+
       {/* Advanced Chart with Integrated Stats */}
       <div className="mb-8">
         <Chart

tailwind.config.ts

@@ -27,11 +27,16 @@ const config: Config = {
           '0%': { opacity: '0' },
           '100%': { opacity: '1' },
         },
+        shimmer: {
+          '0%': { transform: 'translateX(-100%)' },
+          '100%': { transform: 'translateX(400%)' },
+        },
       },
       animation: {
         'cell-highlight': 'cell-highlight 0.5s ease forwards',
         'cell-flash': 'cell-flash 0.6s ease forwards',
         'fade-in': 'fade-in 150ms ease-out',
+        shimmer: 'shimmer 1.2s ease-in-out infinite',
       },
       fontFamily: {
         sans: ['var(--font-plus-jakarta-sans)', 'system-ui', 'sans-serif'],