refactor: address review feedback — extract date helper, rename listener

src/services/player-service.js

@@ -4,6 +4,12 @@ const { fetchPlayerDataHTTP, parsePlayerData } = require('../scrapers/player-htt
 const { calculatePredictedRating } = require('./rating-calculator');
 const logger = require('../logger');
 
+function formatDisplayDate(dateStr) {
+  return new Date(dateStr).toLocaleDateString('en-US', {
+    day: '2-digit', month: 'short', year: 'numeric'
+  });
+}
+
 // Derives previous-month rating and the delta to it. Prefers PDGA's reported
 // rating_change (canonical), falls back to our own monthly snapshots when
 // rating_change is missing — common for players whose latest scrape failed.
@@ -194,9 +200,7 @@ async function getAllRatingsFromDB(progressCallback = null) {
           playerData.ratingHistory = rawHistory.map(row => ({
             date: row.date,
             rating: row.rating,
-            displayDate: new Date(row.date).toLocaleDateString('en-US', {
-              day: '2-digit', month: 'short', year: 'numeric'
-            })
+            displayDate: formatDisplayDate(row.date)
           }));
           // Re-derive now that history is attached — bulk path skipped includeMonthlyHistory
           const derived = deriveMonthlyDeltas(playerData.rating, player.rating_change, playerData.monthlyHistory);
@@ -354,5 +358,6 @@ module.exports = {
   getPredictedRatingFromDB,
   getAllRatingsFromDB,
   refreshAllPlayersInDB,
-  computeKpis
+  computeKpis,
+  formatDisplayDate
 };