fix: improve campaign stats, shared chart components, and i18n coverage

- Extract shared chart constants to constants/charts.ts
- Add TREND_STYLES to stats/constants.ts for reuse
- Fix useChartColors with MutationObserver for theme changes
- Fix DailyChart date parsing to prevent timezone shift
- Add truncate to StatCard value for overflow safety
- Fix CampaignCard copy feedback inside try block
- Add NaN validation and staleTime to AdminCampaignStats
- Replace hardcoded strings with i18n keys in Referral page
- Add missing i18n keys across all 4 locales (en, ru, zh, fa)
- Add sales stats route to AdminPanel and App router

src/components/partner/CampaignCard.tsx

@@ -56,12 +56,15 @@ export function CampaignCard({ campaign }: CampaignCardProps) {
       try {
         await copyToClipboard(url);
         haptic.notification('success');
+        setCopiedLink(key);
+        clearTimeout(copyTimerRef.current);
+        copyTimerRef.current = setTimeout(
+          () => setCopiedLink(null),
+          PARTNER_STATS.COPY_FEEDBACK_MS,
+        );
       } catch {
         haptic.notification('error');
       }
-      setCopiedLink(key);
-      clearTimeout(copyTimerRef.current);
-      copyTimerRef.current = setTimeout(() => setCopiedLink(null), PARTNER_STATS.COPY_FEEDBACK_MS);
     },
     [haptic],
   );