change dateCreated to a string (from a Date object, which persists as a Date object)

src/db/tables/index.ts

@@ -1,6 +1,6 @@
 export type Account = {
   id?: number; // auto-generated by Dexie
-  dateCreated: Date;
+  dateCreated: string;
   derivationPath: string;
   identity: string;
   publicKeyHex: string;