MSAL Browser 2.28+ requires explicit initialize() before handleRedirectPromise()
or loginRedirect(). Without it the authorization request is generated with
missing parameters, causing AADSTS90014.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
MSAL fails to persist PKCE state in sessionStorage across redirects
in some browsers. Cookie fallback ensures auth state survives the
Azure AD redirect loop.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>