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/MapsView.vue

@@ -3,6 +3,7 @@ import { ref, onMounted } from 'vue'
 import { useApi } from '@/composables/useApi'
 import type { MapEntry } from '@/types'
 import { Map, Upload, Trash2, RefreshCw } from 'lucide-vue-next'
+import { safeFileSize } from '@/utils/formatters'
 
 const api = useApi()
 
@@ -10,8 +11,7 @@ const maps = ref<MapEntry[]>([])
 const isLoading = ref(false)
 
 function formatSize(bytes: number): string {
-  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(0)} KB`
-  return `${(bytes / (1024 * 1024)).toFixed(1)} MB`
+  return safeFileSize(bytes)
 }
 
 function typeBadgeClass(type: string): string {