web/dialog: css for small dialog

- moved backdrop to each dialog
- dialog is now closable by clicking the backdrop
- added meowbalt to dialogs
- added more meowbalt assets & components
- added "main" boolean to indicate the main action button in a list of buttons

web/src/components/save/buttons/DownloadButton.svelte

@@ -18,11 +18,13 @@
     let defaultErrorPopup = {
         id: "save-error",
         type: "small",
+        meowbalt: "error",
         title: "",
         bodySubText: "",
         buttons: [{
             text: $t("general.gotit"),
             color: "gray",
+            main: true,
             action: () => {},
         }]
     }