feat(chat): add transient presence flash and 5s reconnect grace period

backend/chat/src/handlers/handlers.go

@@ -1829,7 +1829,7 @@ func HandleAdminChatLog(deps *Dependencies) http.HandlerFunc {
 			limit = parsedLimit
 		}
 
-		dbQuery := deps.DB.Model(&db.Message{})
+		dbQuery := deps.DB.Model(&db.Message{}).Where("type <> ?", "system")
 		if room != "" {
 			dbQuery = dbQuery.Where("room = ?", room)
 		}