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/WipeHistoryView.vue

@@ -2,6 +2,7 @@
 import { onMounted } from 'vue'
 import { useWipeStore } from '@/stores/wipe'
 import { History, RefreshCw } from 'lucide-vue-next'
+import { safeDate } from '@/utils/formatters'
 
 const wipeStore = useWipeStore()
 
@@ -85,7 +86,7 @@ onMounted(() => {
               </span>
             </td>
             <td class="px-4 py-3 text-sm text-neutral-400">
-              {{ wipe.started_at ? new Date(wipe.started_at).toLocaleString() : '\u2014' }}
+              {{ safeDate(wipe.started_at, '\u2014') }}
             </td>
             <td class="px-4 py-3 text-sm text-neutral-400 font-mono">
               {{ duration(wipe.started_at, wipe.completed_at) }}