fix: serialize feedback date ranges in state

Nuxt useState is serialized through the payload, so the state value should stay JSON-safe. Store ISO strings there and expose Date objects through a computed wrapper so consumers keep the same API without relying on Date instances surviving hydration.

The default range also uses the same startOfDay/endOfDay normalization as setDateRange. That keeps the first "Last 30 days" window aligned with picker and preset updates instead of using raw timestamps.

Docs: https://nuxt.com/docs/4.x/getting-started/state-management

Docs: https://nuxt.com/docs/api/composables/use-state

Author: onmax

app/composables/useDateRange.ts

@@ -5,16 +5,29 @@ export interface DateRange {
   end: Date
 }
 
+interface SerializedDateRange {
+  start: string
+  end: string
+}
+
 export function useDateRange() {
-  const dateRange = useState<DateRange>('feedback-date-range', () => ({
-    start: subDays(new Date(), 30),
-    end: new Date()
+  const serializedDateRange = useState<SerializedDateRange>('feedback-date-range', () => {
+    const end = endOfDay(new Date())
+    return {
+      start: startOfDay(subDays(end, 30)).toISOString(),
+      end: end.toISOString()
+    }
+  })
+
+  const dateRange = computed<DateRange>(() => ({
+    start: new Date(serializedDateRange.value.start),
+    end: new Date(serializedDateRange.value.end)
   }))
 
   const setDateRange = (range: DateRange) => {
-    dateRange.value = {
-      start: startOfDay(range.start),
-      end: endOfDay(range.end)
+    serializedDateRange.value = {
+      start: startOfDay(range.start).toISOString(),
+      end: endOfDay(range.end).toISOString()
     }
   }