web: updated api endpoint & params, default instance override

- dialogs can be undismissable now (impossible to click away by pressing the bg behind it)
- added security warning about api override
- moved default api url to env
- added new processing settings page

web/src/lib/download.ts

@@ -9,7 +9,7 @@ import { createDialog } from "$lib/dialogs";
 import type { DialogInfo } from "$lib/types/dialog";
 
 export const openSavingDialog = (url: string, body: string | void) => {
-    let dialogData: DialogInfo = {
+    const dialogData: DialogInfo = {
         type: "saving",
         id: "saving",
         url