Fix server action structuur in login en tenants pagina's

Inline server actions in page components veroorzaken runtime errors.
Verplaatst naar aparte actions.ts / logout.ts bestanden.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/tenants/logout.ts

@@ -0,0 +1,9 @@
+"use server";
+
+import { redirect } from "next/navigation";
+import { destroySession } from "../../lib/auth";
+
+export async function logout() {
+  await destroySession();
+  redirect("/login");
+}