feat: add admin sales statistics dashboard with 5 analytics tabs

- Add sales stats API client with typed interfaces for all endpoints
- Implement AdminSalesStats page with summary cards and period selector
- Add TrialsTab with provider breakdown donut chart and daily area chart
- Add SalesTab with tariff/period breakdown and daily revenue chart
- Add RenewalsTab with period comparison and trend indicators
- Add AddonsTab with package breakdown bar chart
- Add DepositsTab with payment method breakdown bar chart
- Add SimpleBarChart, SimpleAreaChart, DonutChart components
- Add PeriodSelector with preset periods and custom date range
- Full responsive design (mobile/tablet/desktop/TG Mini App)
- ARIA accessibility (tablist, tab, tabpanel, aria-selected)
- Error handling with isError on all queries
- Empty data guards on all chart components
- i18n support across all 4 locales (en, ru, zh, fa)

src/components/sales-stats/SimpleAreaChart.tsx

@@ -0,0 +1,114 @@
+import { useMemo } from 'react';
+import { useTranslation } from 'react-i18next';
+import {
+  Area,
+  AreaChart,
+  CartesianGrid,
+  ResponsiveContainer,
+  Tooltip,
+  XAxis,
+  YAxis,
+} from 'recharts';
+
+import { SALES_STATS } from '../../constants/salesStats';
+import { useChartColors } from '../../hooks/useChartColors';
+
+interface SimpleAreaChartProps {
+  data: { date: string; value: number }[];
+  title: string;
+  color?: string;
+  chartId: string;
+  valueLabel?: string;
+  height?: number;
+}
+
+export function SimpleAreaChart({
+  data,
+  title,
+  color,
+  chartId,
+  valueLabel,
+  height = SALES_STATS.CHART.HEIGHT,
+}: SimpleAreaChartProps) {
+  const { t, i18n } = useTranslation();
+  const colors = useChartColors();
+  const strokeColor = color || colors.earnings;
+
+  const chartData = useMemo(
+    () =>
+      data.map((item) => ({
+        ...item,
+        label: new Date(item.date + 'T00:00:00').toLocaleDateString(i18n.language, {
+          month: 'short',
+          day: 'numeric',
+        }),
+      })),
+    [data, i18n.language],
+  );
+
+  if (data.length === 0) {
+    return (
+      <div className="bento-card">
+        <h4 className="mb-3 text-sm font-semibold text-dark-200">{title}</h4>
+        <div className="flex items-center justify-center text-sm text-dark-400" style={{ height }}>
+          {t('common.noData')}
+        </div>
+      </div>
+    );
+  }
+
+  return (
+    <div className="bento-card">
+      <h4 className="mb-3 text-sm font-semibold text-dark-200">{title}</h4>
+      <ResponsiveContainer width="100%" height={height}>
+        <AreaChart data={chartData} margin={SALES_STATS.CHART.MARGIN}>
+          <defs>
+            <linearGradient id={`gradient-${chartId}`} x1="0" y1="0" x2="0" y2="1">
+              <stop
+                offset={SALES_STATS.GRADIENT.START_OFFSET}
+                stopColor={strokeColor}
+                stopOpacity={SALES_STATS.GRADIENT.START_OPACITY}
+              />
+              <stop
+                offset={SALES_STATS.GRADIENT.END_OFFSET}
+                stopColor={strokeColor}
+                stopOpacity={SALES_STATS.GRADIENT.END_OPACITY}
+              />
+            </linearGradient>
+          </defs>
+          <CartesianGrid strokeDasharray={SALES_STATS.GRID_DASH} stroke={colors.grid} />
+          <XAxis
+            dataKey="label"
+            tick={{ fill: colors.tick, fontSize: SALES_STATS.AXIS.TICK_FONT_SIZE }}
+            tickLine={false}
+            interval="preserveStartEnd"
+          />
+          <YAxis
+            tick={{ fill: colors.tick, fontSize: SALES_STATS.AXIS.TICK_FONT_SIZE }}
+            tickLine={false}
+            axisLine={false}
+            width={SALES_STATS.AXIS.WIDTH}
+            allowDecimals={false}
+          />
+          <Tooltip
+            contentStyle={{
+              backgroundColor: colors.tooltipBg,
+              border: `1px solid ${colors.tooltipBorder}`,
+              borderRadius: SALES_STATS.TOOLTIP.BORDER_RADIUS,
+              fontSize: SALES_STATS.TOOLTIP.FONT_SIZE,
+            }}
+            labelStyle={{ color: colors.label }}
+            formatter={(value: number | undefined) => [value ?? 0, valueLabel || '']}
+          />
+          <Area
+            type="monotone"
+            dataKey="value"
+            stroke={strokeColor}
+            fill={`url(#gradient-${chartId})`}
+            strokeWidth={SALES_STATS.STROKE_WIDTH}
+          />
+        </AreaChart>
+      </ResponsiveContainer>
+    </div>
+  );
+}