Make sync behavior apply on first sync only, finish MVP create/update bidirectional sync for Heroku

backend/src/db/migrations/20240307232900_integration-last-used.ts

@@ -0,0 +1,15 @@
+import { Knex } from "knex";
+
+import { TableName } from "../schemas";
+
+export async function up(knex: Knex): Promise<void> {
+  await knex.schema.alterTable(TableName.Integration, (t) => {
+    t.datetime("lastUsed");
+  });
+}
+
+export async function down(knex: Knex): Promise<void> {
+  await knex.schema.alterTable(TableName.Integration, (t) => {
+    t.dropColumn("lastUsed");
+  });
+}