ax(mining): rename wg to waitGroup in collectMinerStats

AX Principle 1: predictable names over short names. `wg` requires
domain knowledge to decode; `waitGroup` is self-documenting.

Co-Authored-By: Charon <charon@lethean.io>

pkg/mining/manager.go

@@ -578,11 +578,11 @@ func (m *Manager) collectMinerStats() {
 	now := time.Now()
 
 	// Collect stats from all miners in parallel
-	var wg sync.WaitGroup
+	var waitGroup sync.WaitGroup
 	for _, mi := range miners {
-		wg.Add(1)
+		waitGroup.Add(1)
 		go func(miner Miner, minerType string) {
-			defer wg.Done()
+			defer waitGroup.Done()
 			defer func() {
 				if r := recover(); r != nil {
 					logging.Error("panic in single miner stats collection", logging.Fields{
@@ -594,7 +594,7 @@ func (m *Manager) collectMinerStats() {
 			m.collectSingleMinerStats(miner, minerType, now, databaseEnabled)
 		}(mi.miner, mi.minerType)
 	}
-	wg.Wait()
+	waitGroup.Wait()
 }
 
 // statsRetryCount is the number of retries for transient stats failures.