Incorporated pkce into auth.

src/pkce.js

@@ -1,24 +0,0 @@
-// pkce.js
-import crypto from "node:crypto";
-
-function base64UrlEncode(buf) {
-  return buf
-    .toString("base64")
-    .replace(/\+/g, "-")
-    .replace(/\//g, "_")
-    .replace(/=+$/g, "");
-}
-
-/**
- * RFC7636 PKCE (S256)
- * @returns {{ verifier: string, challenge: string, challengeMethod: "S256" }}
- */
-export function generatePkce() {
-  // 32 bytes -> ~43 chars base64url, within RFC7636 43..128 range
-  const verifier = base64UrlEncode(crypto.randomBytes(32));
-  const challenge = base64UrlEncode(
-    crypto.createHash("sha256").update(verifier).digest()
-  );
-
-  return { verifier, challenge, challengeMethod: "S256" };
-}