refactor: add save()/savePlayer() methods on game instances

Wrap free persistence functions in instance methods for cleaner call
sites (gi.save() instead of saveGame(gi.queries, gi.game)). Methods
log errors via zerolog before returning them.

snake/loop.go

@@ -62,7 +62,7 @@ func (si *SnakeGameInstance) countdownPhase() {
 				si.game.Status = StatusInProgress
 
 				if si.queries != nil {
-					saveSnakeGame(si.queries, si.game) //nolint:errcheck
+					si.save() //nolint:errcheck
 				}
 				si.gameMu.Unlock()
 				si.notify()
@@ -123,7 +123,7 @@ func (si *SnakeGameInstance) gamePhase() {
 			if time.Since(lastInput) > inactivityLimit {
 				si.game.Status = StatusFinished
 				if si.queries != nil {
-					saveSnakeGame(si.queries, si.game) //nolint:errcheck
+					si.save() //nolint:errcheck
 				}
 				si.gameMu.Unlock()
 				si.notify()
@@ -193,7 +193,7 @@ func (si *SnakeGameInstance) gamePhase() {
 
 			// Throttle DB saves: persist on game over or every 2 seconds
 			if si.queries != nil && (gameOver || time.Since(lastSave) >= 2*time.Second) {
-				saveSnakeGame(si.queries, si.game) //nolint:errcheck
+				si.save() //nolint:errcheck
 				lastSave = time.Now()
 			}