fix too many accounts error because the worker was behind a Cloudflare call, add username change

apps/www/vitest.config.ts

@@ -6,6 +6,22 @@ export default defineConfig({
 		cloudflareTest({
 			wrangler: { configPath: `${__dirname}/wrangler.jsonc` },
 			miniflare: {
+				// Stands in for the `auth` service binding wrangler.jsonc declares — the real
+				// worker isn't part of this project's test run, and without an override the
+				// runtime refuses to start ("no such service is defined"). It echoes the
+				// forwarded `cf-connecting-ip` back so a test can assert the browser's IP
+				// actually survives the hop (see src/upstream.ts `postAuthForm`); every other
+				// auth call in the tests fails before reaching it.
+				serviceBindings: {
+					AUTH: (request: Request) =>
+						new Response(
+							JSON.stringify({
+								error: 'invalid_grant',
+								error_description: request.headers.get('cf-connecting-ip') ?? 'no ip',
+							}),
+							{ status: 400, headers: { 'content-type': 'application/json' } }
+						),
+				},
 				bindings: {
 					ENVIRONMENT: 'VITEST',
 					// The Turnstile keypair is NOT bound here: both keys come from the Secrets