Add redirect override for auth login

[krowvin]

@tsressin

[tsressin]

I found this redirect code does not respect the query string and does not return to the page properly when a query string is needed.

              <Button
                title="You must login to access this page."
                color="white"
                onClick={() => {
                  auth.login({ redirectUri: window.location.href });
                }}
              >
                Login
              </Button>

For example, this page returns to this.

[msweier]

A bit out of my wheelhouse, so claude is helping me. Overall looks good, using session storage is a good way to to store the return URL. The auth docs need to be updated though (this came after this PR was started). The redirectUri: window.location.href should be updated to redirectUri: window.location.origin to show users how to redirect to the current page.

The redirectUri could mean the stable registered callback in the config or the page return in the login() call. So maybe a JSDoc line on AuthLoginOptions.redirectUri in AuthContext.tsx like:

export interface AuthLoginOptions {
  /**
   * In-app URL to return the user to after sign-in. Stored locally and
   * restored after the callback. It is NOT sent to the identity provider.
   * The registered OIDC callback stays whatever you set as `redirectUri`
   * on createKeycloakAuthMethod().
   */
  redirectUri?: string;
}

[msweier]

Looks good, thanks!