feat: SSR compatibility for journey-client and oidc-client (PoC)

Make journey-client and oidc-client importable and usable in Node.js/SSR
environments by eliminating eager browser global references and decoupling
PKCE generation from sessionStorage.

Storage: Replace eager sessionStorage/localStorage references with lazy
globalThis access via getBrowserStorage(). Add configurable storage option
to JourneyClientConfig so SSR callers can provide a custom noop adapter.

PKCE: Decouple generation from storage — createAuthorizeUrl now returns
{ url, verifier, state } instead of writing to sessionStorage. Callers
persist PKCE values however they choose (cookies, server session, etc.).
Token exchange accepts optional pkceValues parameter to skip sessionStorage.

Guard redirect() with typeof window check for server environments.
Export createJourneyObject for client-side step reconstitution.

SvelteKit PoC in e2e/svelte-app demonstrates the full flow:
server-side journey start, client-side credential submission,
server-side PKCE authorize URL generation with cookie-based verifier
persistence, and server-side token exchange against the AM mock API.

Author: ryanbas21

e2e/oidc-app/src/utils/oidc-app.ts

@@ -88,14 +88,14 @@ export async function oidcApp({ config, urlParams }) {
   });
 
   document.getElementById('login-redirect').addEventListener('click', async () => {
-    const authorizeUrl = await oidcClient.authorize.url();
-    if (typeof authorizeUrl !== 'string' && 'error' in authorizeUrl) {
-      console.error('Authorization URL Error:', authorizeUrl);
-      displayError(authorizeUrl);
+    const authorizeResult = await oidcClient.authorize.url();
+    if ('error' in authorizeResult) {
+      console.error('Authorization URL Error:', authorizeResult);
+      displayError(authorizeResult);
       return;
     } else {
-      console.log('Authorization URL:', authorizeUrl);
-      window.location.assign(authorizeUrl);
+      console.log('Authorization URL:', authorizeResult.url);
+      window.location.assign(authorizeResult.url);
     }
   });
 

e2e/svelte-app/.svelte-kit/ambient.d.ts

@@ -0,0 +1,31 @@
+export { matchers } from './matchers.js';
+
+export const nodes = [
+	() => import('./nodes/0'),
+	() => import('./nodes/1'),
+	() => import('./nodes/2'),
+	() => import('./nodes/3')
+];
+
+export const server_loads = [];
+
+export const dictionary = {
+		"/": [~2],
+		"/callback": [~3]
+	};
+
+export const hooks = {
+	handleError: (({ error }) => { console.error(error) }),
+	
+	reroute: (() => {}),
+	transport: {}
+};
+
+export const decoders = Object.fromEntries(Object.entries(hooks.transport).map(([k, v]) => [k, v.decode]));
+export const encoders = Object.fromEntries(Object.entries(hooks.transport).map(([k, v]) => [k, v.encode]));
+
+export const hash = false;
+
+export const decode = (type, value) => decoders[type](value);
+
+export { default as root } from '../root.js';

e2e/svelte-app/.svelte-kit/generated/client-optimized/app.js

@@ -0,0 +1 @@
+export const matchers = {};

e2e/svelte-app/.svelte-kit/generated/client-optimized/matchers.js

@@ -0,0 +1 @@
+export { default as component } from "../../../../src/routes/+layout.svelte";

e2e/svelte-app/.svelte-kit/generated/client-optimized/nodes/0.js

@@ -0,0 +1 @@
+export { default as component } from "../../../../src/routes/+page.svelte";

e2e/svelte-app/.svelte-kit/generated/client-optimized/nodes/1.js

@@ -0,0 +1 @@
+export { default as component } from "../../../../src/routes/callback/+page.svelte";

e2e/svelte-app/.svelte-kit/generated/client-optimized/nodes/2.js

@@ -0,0 +1,31 @@
+export { matchers } from './matchers.js';
+
+export const nodes = [
+	() => import('./nodes/0'),
+	() => import('./nodes/1'),
+	() => import('./nodes/2'),
+	() => import('./nodes/3')
+];
+
+export const server_loads = [];
+
+export const dictionary = {
+		"/": [~2],
+		"/callback": [~3]
+	};
+
+export const hooks = {
+	handleError: (({ error }) => { console.error(error) }),
+	
+	reroute: (() => {}),
+	transport: {}
+};
+
+export const decoders = Object.fromEntries(Object.entries(hooks.transport).map(([k, v]) => [k, v.decode]));
+export const encoders = Object.fromEntries(Object.entries(hooks.transport).map(([k, v]) => [k, v.encode]));
+
+export const hash = false;
+
+export const decode = (type, value) => decoders[type](value);
+
+export { default as root } from '../root.js';

e2e/svelte-app/.svelte-kit/generated/client-optimized/nodes/3.js

@@ -0,0 +1 @@
+export const matchers = {};