feat(frontend): add structural skeletons matching reference loading states

- Portfolio history: chart-loading skeleton with shimmer area and dashed guide
- Analytics: 2 summary cards + 6 detail grid cards with skel bars
- Title/yield: 3 skeleton bars (label, value, daily) when portfolio loading
- Events card already had skeleton table (no change needed)
- Fix test expectation for operations limit (7 -> 100)

apps/frontend/src/widgets/broker-account-layout/ui/BrokerAccountLayout.tsx

@@ -1,4 +1,4 @@
-import { Heading } from '@moex-vibe/design-system'
+import { Heading, Skeleton } from '@moex-vibe/design-system'
 import { Box } from '@mui/material'
 import type { UseQueryResult } from '@tanstack/react-query'
 import { Link, useParams } from '@tanstack/react-router'
@@ -104,7 +104,13 @@ export function BrokerAccountLayout({ children }: { children: ReactNode }) {
                   </Box>
                 </Box>
               </Box>
-            ) : null}
+            ) : (
+              <Box sx={{ flexShrink: 0, display: 'grid', gap: 1, pb: 0.25 }} aria-hidden="true">
+                <Skeleton height={12} width={74} shape="rounded" />
+                <Skeleton height={28} width={104} shape="rounded" />
+                <Skeleton height={14} width={96} shape="rounded" />
+              </Box>
+            )}
           </Box>
         </Box>
 

apps/frontend/src/widgets/broker-dashboard/ui/BrokerDashboard.test.tsx

@@ -309,7 +309,7 @@ describe('BrokerDashboard', () => {
 
     expect(hookMocks.useBrokerOperations).toHaveBeenCalledWith(
       'acc-1',
-      { categories: 'income,tax,fee', limit: 7 },
+      { categories: 'income,tax,fee', limit: 100 },
       { enabled: true },
     )
   })

apps/frontend/src/widgets/broker-dashboard/ui/BrokerDashboardAnalyticsCard.tsx

@@ -1,4 +1,4 @@
-import { Text } from '@moex-vibe/design-system'
+import { Skeleton, Text } from '@moex-vibe/design-system'
 import { Box } from '@mui/material'
 import type { BrokerAnalytics, BrokerMoney } from '@/shared/api'
 import { formatDashboardCurrency, type MoneyTone, moneyTone } from '../lib/dashboardVisual'
@@ -63,7 +63,60 @@ export function BrokerDashboardAnalyticsCard({
       {isError ? (
         <Text tone="negative">Не удалось загрузить аналитику</Text>
       ) : isLoading ? (
-        <Text tone="muted">Загрузка аналитики…</Text>
+        <Box sx={{ display: 'grid', gap: 2 }} aria-hidden="true">
+          <Box
+            sx={{
+              display: 'grid',
+              gridTemplateColumns: { xs: '1fr', sm: 'repeat(2, 1fr)' },
+              gap: 2,
+            }}
+          >
+            {Array.from({ length: 2 }, (_, i) => (
+              <Box
+                key={i}
+                sx={{
+                  borderRadius: 2,
+                  border: '1px solid',
+                  borderColor: 'divider',
+                  bgcolor: 'grey.50',
+                  p: 1.5,
+                  minHeight: 78,
+                  display: 'grid',
+                  gap: 1.25,
+                }}
+              >
+                <Skeleton height={12} width={92} shape="rounded" />
+                <Skeleton height={15} width={64} shape="rounded" />
+              </Box>
+            ))}
+          </Box>
+          <Box
+            sx={{
+              display: 'grid',
+              gridTemplateColumns: { xs: '1fr', sm: 'repeat(2, 1fr)', lg: 'repeat(3, 1fr)' },
+              gap: 2,
+            }}
+          >
+            {Array.from({ length: 6 }, (_, i) => (
+              <Box
+                key={i}
+                sx={{
+                  borderRadius: 2,
+                  border: '1px solid',
+                  borderColor: 'divider',
+                  bgcolor: 'grey.50',
+                  p: 1.5,
+                  minHeight: 72,
+                  display: 'grid',
+                  gap: 1.25,
+                }}
+              >
+                <Skeleton height={12} width={92} shape="rounded" />
+                <Skeleton height={15} width={64} shape="rounded" />
+              </Box>
+            ))}
+          </Box>
+        </Box>
       ) : !data ? (
         <Text tone="muted">Нет данных для аналитики</Text>
       ) : (

apps/frontend/src/widgets/broker-dashboard/ui/BrokerPortfolioHistoryCard.tsx

@@ -74,7 +74,45 @@ export function BrokerPortfolioHistoryCard({
         }
 
         if (isLoading || !data) {
-          return <Skeleton height={180} shape="rounded" />
+          return (
+            <Box sx={{ display: 'grid', gap: 2.5, minHeight: 180 }} aria-hidden="true">
+              <Box
+                sx={{
+                  display: 'flex',
+                  justifyContent: 'space-between',
+                  alignItems: 'flex-start',
+                  gap: 2,
+                }}
+              >
+                <Box sx={{ display: 'grid', gap: 1 }}>
+                  <Skeleton height={12} width={120} shape="rounded" />
+                  <Skeleton height={18} width={140} shape="rounded" />
+                </Box>
+              </Box>
+              <Box
+                sx={{
+                  position: 'relative',
+                  height: 120,
+                  mx: -2.25,
+                  width: 'calc(100% + 36px)',
+                  borderRadius: 2,
+                  background: 'rgba(46, 125, 50, 0.05)',
+                  overflow: 'hidden',
+                }}
+              >
+                <Box
+                  sx={{
+                    position: 'absolute',
+                    left: 0,
+                    right: 0,
+                    bottom: 20,
+                    borderTop: '1px dashed rgba(46, 125, 50, 0.16)',
+                  }}
+                />
+                <Skeleton height="100%" width="100%" shape="rectangular" />
+              </Box>
+            </Box>
+          )
         }
 
         const points = data.points