refactor: use Go duration strings for QUEUE_MAX_AGE and MESSAGE_MAX_AGE

Change config from integer seconds to Go duration strings (e.g. '720h')
parsed via time.ParseDuration, consistent with SESSION_IDLE_TIMEOUT.
Default remains 30 days (720h).

internal/handlers/handlers.go

@@ -204,16 +204,39 @@ func (hdlr *Handlers) runCleanup(
 	hdlr.pruneQueuesAndMessages(ctx)
 }
 
+// parseDurationConfig parses a Go duration string,
+// returning zero on empty input and logging on error.
+func (hdlr *Handlers) parseDurationConfig(
+	name, raw string,
+) time.Duration {
+	if raw == "" {
+		return 0
+	}
+
+	dur, err := time.ParseDuration(raw)
+	if err != nil {
+		hdlr.log.Error(
+			"invalid duration config, skipping",
+			"name", name, "value", raw, "error", err,
+		)
+
+		return 0
+	}
+
+	return dur
+}
+
 // pruneQueuesAndMessages removes old client_queues entries
 // per QUEUE_MAX_AGE and prunes messages per MESSAGE_MAX_AGE.
 func (hdlr *Handlers) pruneQueuesAndMessages(
 	ctx context.Context,
 ) {
-	queueMaxAge := hdlr.params.Config.QueueMaxAge
+	queueMaxAge := hdlr.parseDurationConfig(
+		"QUEUE_MAX_AGE",
+		hdlr.params.Config.QueueMaxAge,
+	)
 	if queueMaxAge > 0 {
-		queueCutoff := time.Now().Add(
-			-time.Duration(queueMaxAge) * time.Second,
-		)
+		queueCutoff := time.Now().Add(-queueMaxAge)
 
 		pruned, err := hdlr.params.Database.
 			PruneOldQueueEntries(ctx, queueCutoff)
@@ -229,11 +252,12 @@ func (hdlr *Handlers) pruneQueuesAndMessages(
 		}
 	}
 
-	messageMaxAge := hdlr.params.Config.MessageMaxAge
+	messageMaxAge := hdlr.parseDurationConfig(
+		"MESSAGE_MAX_AGE",
+		hdlr.params.Config.MessageMaxAge,
+	)
 	if messageMaxAge > 0 {
-		msgCutoff := time.Now().Add(
-			-time.Duration(messageMaxAge) * time.Second,
-		)
+		msgCutoff := time.Now().Add(-messageMaxAge)
 
 		pruned, err := hdlr.params.Database.
 			PruneOldMessages(ctx, msgCutoff)