fix: Replace unsafe .toFixed() calls with safeFixed() in analytics views

- AnalyticsView: avg_players, uptime_percentage
- WipeAnalyticsView: success_rate, population curve, durations, CSV export
- PlayerRetentionView: retention percentages, session duration, tooltip
- MapAnalyticsView: rotation effectiveness, performance metrics, table

All analytics views now use safe formatter utilities with optional chaining
to prevent null/undefined runtime errors when displaying numeric data.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/views/admin/StoreRevenueView.vue

@@ -5,6 +5,7 @@ import * as echarts from 'echarts'
 import type { ECharts } from 'echarts'
 import { useApi } from '@/composables/useApi'
 import type { StoreTransaction } from '@/types'
+import { safeCurrency, safeDate } from '@/utils/formatters'
 
 const api = useApi()
 
@@ -41,7 +42,7 @@ const filteredTransactions = computed(() => {
 // Format currency properly
 const formatCurrency = (amount: number, currency: string = 'USD'): string => {
   const symbol = currency === 'USD' ? '$' : currency
-  return `${symbol}${amount.toFixed(2)}`
+  return safeCurrency(amount, symbol)
 }
 
 // Status badge color classes
@@ -58,13 +59,7 @@ const statusBadgeClass = (status: string): string => {
 
 // Format date for display
 const formatDate = (dateStr: string): string => {
-  return new Date(dateStr).toLocaleDateString('en-US', {
-    year: 'numeric',
-    month: 'short',
-    day: 'numeric',
-    hour: '2-digit',
-    minute: '2-digit'
-  })
+  return safeDate(dateStr, '—')
 }
 
 // Load transactions
@@ -122,8 +117,8 @@ const renderRevenueChart = () => {
       borderColor: '#2a2a2a',
       textStyle: { color: '#e5e5e5' },
       formatter: (params: any) => {
-        const value = params[0].data
-        return `${params[0].axisValue}<br/>Revenue: $${value.toFixed(2)}`
+        const value = params[0]?.data
+        return `${params[0]?.axisValue ?? 'Unknown'}<br/>Revenue: ${safeCurrency(value, '$')}`
       }
     },
     grid: {