fix(invite): add secure flag to pf_invite cookie for HTTPS production

src/app/join/page.tsx

@@ -21,6 +21,7 @@ async function submitCode(formData: FormData) {
   const cookieStore = await cookies();
   cookieStore.set("pf_invite", code, {
     httpOnly: true,
+    secure: process.env.NODE_ENV === "production",
     sameSite: "lax",
     maxAge: 60 * 60, // 1 hour
     path: "/",