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],
   );

src/components/stats/DailyChart.tsx

@@ -42,7 +42,7 @@ export function DailyChart({ data, chartId, title, earningsLabel, countLabel }:
       data.map((item) => ({
         ...item,
         earnings_display: item.earnings_kopeks / PARTNER_STATS.KOPEKS_DIVISOR,
-        label: new Date(item.date).toLocaleDateString(i18n.language, {
+        label: new Date(item.date + 'T00:00:00').toLocaleDateString(i18n.language, {
           month: 'short',
           day: 'numeric',
         }),

src/components/stats/PeriodComparison.tsx

@@ -1,6 +1,7 @@
 import { useTranslation } from 'react-i18next';
 
 import type { PeriodComparison as PeriodComparisonType } from './types';
+import { TREND_STYLES } from './constants';
 import { PARTNER_STATS } from '../../constants/partner';
 import { useCurrency } from '../../hooks/useCurrency';
 
@@ -12,16 +13,6 @@ interface PeriodComparisonProps {
   comparisonLabel?: string;
 }
 
-const TREND_ARROW_UP = '\u2191';
-const TREND_ARROW_DOWN = '\u2193';
-const TREND_ARROW_STABLE = '\u2192';
-
-const TREND_STYLES = {
-  up: { arrow: TREND_ARROW_UP, className: 'text-success-400' },
-  down: { arrow: TREND_ARROW_DOWN, className: 'text-error-400' },
-  stable: { arrow: TREND_ARROW_STABLE, className: 'text-dark-400' },
-} as const;
-
 interface TrendBadgeProps {
   trend: 'up' | 'down' | 'stable';
   percent: number;

src/components/stats/StatCard.tsx

@@ -21,7 +21,9 @@ export function StatCard({
         {icon}
         <span>{label}</span>
       </div>
-      <div className={`mt-1 text-base font-semibold sm:text-lg ${valueClassName}`}>{value}</div>
+      <div className={`mt-1 truncate text-base font-semibold sm:text-lg ${valueClassName}`}>
+        {value}
+      </div>
     </div>
   );
 }

src/components/stats/constants.ts

@@ -0,0 +1,5 @@
+export const TREND_STYLES = {
+  up: { arrow: '\u2191', className: 'text-success-400' },
+  down: { arrow: '\u2193', className: 'text-error-400' },
+  stable: { arrow: '\u2192', className: 'text-dark-400' },
+} as const;