fix: pre-compute stats to make the API endpoint fast

frontend/server/api/stats.ts

@@ -1,14 +1,29 @@
 import type { MongoClient } from 'mongodb'
 import { connectToDatabase, fetchLatestPatch, getAvailablePlatforms } from '../utils/mongo'
 
+interface StatsDocument {
+  patch: string
+  total: number
+  platforms: Record<string, number>
+  updatedAt: Date
+}
+
 async function fetchGameCount(client: MongoClient, patch: string) {
   const database = client.db('matches')
+  const statsCollection = database.collection<StatsDocument>('stats')
 
-  // Check for platform-specific collections
+  // Try to get stats from the pre-computed stats collection
+  const stats = await statsCollection.findOne({ patch })
+
+  if (stats) {
+    return { total: stats.total, platforms: stats.platforms }
+  }
+
+  // Fallback: compute stats from collections if stats document doesn't exist
+  // This handles the migration case where stats weren't pre-computed
   const platforms = await getAvailablePlatforms(client, patch)
 
   if (platforms.length > 0) {
-    // Sum counts from all platform-specific collections
     let totalCount = 0
     const platformCounts: Record<string, number> = {}