fix: use 'client output queue' terminology consistently

Replace ambiguous 'queue' with 'client output queue' throughout
documentation, code comments, log messages, and error strings
added in the queue pruning PR.

internal/handlers/handlers.go

@@ -226,8 +226,9 @@ func (hdlr *Handlers) parseDurationConfig(
 	return dur
 }
 
-// pruneQueuesAndMessages removes old client_queues entries
-// per QUEUE_MAX_AGE and prunes messages per MESSAGE_MAX_AGE.
+// pruneQueuesAndMessages removes old client output queue
+// entries per QUEUE_MAX_AGE and old messages per
+// MESSAGE_MAX_AGE.
 func (hdlr *Handlers) pruneQueuesAndMessages(
 	ctx context.Context,
 ) {
@@ -242,11 +243,11 @@ func (hdlr *Handlers) pruneQueuesAndMessages(
 			PruneOldQueueEntries(ctx, queueCutoff)
 		if err != nil {
 			hdlr.log.Error(
-				"queue pruning failed", "error", err,
+				"client output queue pruning failed", "error", err,
 			)
 		} else if pruned > 0 {
 			hdlr.log.Info(
-				"pruned old queue entries",
+				"pruned old client output queue entries",
 				"deleted", pruned,
 			)
 		}