Add setGenerateJWT method to update JWT generator after initialization

When using JWT auth, the generateJWT function passed to initialize() gets
captured and never updates. This adds a setGenerateJWT export that allows
updating the function reference at any time, fixing #160.

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

Author: franco-zalamena-iterable

src/authorization/authorization.ts

@@ -1192,6 +1192,21 @@ export function initializeWithConfig(initializeParams: InitializeParams) {
     : initialize(authToken);
 }
 
+/**
+ * Updates the JWT generator function used by the SDK.
+ *
+ * This is useful when the outer context that the `generateJWT` callback
+ * closes over changes after `initialize()` has already been called
+ * (e.g., when an upstream auth token is refreshed).
+ *
+ * @param newGenerateJWT - A function that returns a Promise resolving to a JWT string.
+ */
+export function setGenerateJWT(
+  newGenerateJWT: (payload: GenerateJWTPayload) => Promise<string>
+) {
+  generateJWTGlobal = newGenerateJWT;
+}
+
 export function setTypeOfAuthForTestingOnly(authType: TypeOfAuth) {
   if (!authType) {
     setTypeOfAuth(null);