refactor(odeme): update environment variable usage and documentation

Replaced `NEXT_PUBLIC_APP_URL` with `APP_URL` in the payment processing logic to ensure proper runtime access. Updated related documentation to clarify the distinction between build-time and runtime environment variables, emphasizing the importance of using `APP_URL` for callback and webhook URLs. Adjusted references in the codebase to reflect this change, enhancing clarity and functionality in the payment flow.

src/features/odeme/odeme-actions.ts

@@ -4,6 +4,7 @@ import { eq } from "drizzle-orm";
 import { headers } from "next/headers";
 import { redirect } from "next/navigation";
 import { verifySession } from "@/lib/session";
+import { appUrl as siteKok } from "@/lib/app-url";
 import { appDb, schema } from "@/lib/appdb";
 import { URUNLER } from "@/lib/credits";
 import { initializeCheckoutForm, initImzaDurumu } from "@/lib/iyzico";
@@ -47,7 +48,7 @@ export async function baslatOdeme(
   const h = await headers();
   const buyerIp =
     h.get("x-forwarded-for")?.split(",")[0]?.trim() ?? "85.34.78.112";
-  const appUrl = process.env.NEXT_PUBLIC_APP_URL ?? "http://localhost:3000";
+  const appUrl = siteKok();
   const [ad, soyad] = adSoyadAyir(session.user.name ?? "");
 
   let init;