feat: currency selection support (#72)

* initial UI for currency selection

* add task to purge invitation tokens

* group API contracts

* fix type import

* use auth middleware

* add currency setting support (UI)

* use group settings for format currency

* fix casing

frontend/composables/use-formatters.ts

@@ -0,0 +1,21 @@
+const cache = {
+  currency: "",
+};
+
+export function ResetCurrency() {
+  cache.currency = "";
+}
+
+export async function useFormatCurrency() {
+  if (!cache.currency) {
+    const client = useUserApi();
+
+    const { data: group } = await client.group.get();
+
+    if (group) {
+      cache.currency = group.currency;
+    }
+  }
+
+  return (value: number | string) => fmtCurrency(value, cache.currency);
+}