Reapply "Add missing admin action files and navigation links"

This reverts commit 4d515bc400.

src/actions/referral.ts

@@ -27,16 +27,10 @@ import { type CurrencyName, sendCurrency } from "@/lib/services/send-currency";
  * redirects with ?claimed=1. redirect() is called OUTSIDE the try/catch so its
  * internal control-flow throw is never swallowed.
  */
-const VALID_CURRENCIES = new Set<CurrencyName>([
-  "credits",
-  "duckets",
-  "diamonds",
-  "points",
-]);
+const VALID_CURRENCIES = new Set<CurrencyName>(["credits", "duckets", "diamonds", "points"]);
 
 export async function claimReferral(_formData: FormData): Promise<void> {
-  let outcome: "claimed" | "not_enough" | "no_referrals" | "bad_config" | "error" =
-    "error";
+  let outcome: "claimed" | "not_enough" | "no_referrals" | "bad_config" | "error" = "error";
 
   try {
     const session = await auth();