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/platform-admin/AdminDashboard.vue

@@ -3,6 +3,7 @@ import { ref, onMounted } from 'vue'
 import { useApi } from '@/composables/useApi'
 import { useRouter } from 'vue-router'
 import { Key, KeyRound, Users, DollarSign, Server, UserPlus, ArrowRight, ScrollText, CreditCard, MonitorCog } from 'lucide-vue-next'
+import { safeCurrency, safeLocaleString } from '@/utils/formatters'
 
 const api = useApi()
 const router = useRouter()
@@ -36,11 +37,10 @@ const quickLinks = [
 ]
 
 function formatValue(value: number | undefined, format: string): string {
-  if (value == null) return '\u2014'
   if (format === 'currency') {
-    return `$${value.toFixed(2)}`
+    return safeCurrency(value, '$', '\u2014')
   }
-  return value.toLocaleString()
+  return safeLocaleString(value, '\u2014')
 }
 
 async function fetchStats() {