Remove the login box frame and hide "Lost your password?" reliably

- No border or shadow around the login box on wp-login.php (form and
  Microsoft block, also in button-only mode); the white area stays.
- Button-only mode: the "Lost your password?" link is removed through
  lost_password_html_link instead of CSS only, the lostpassword,
  retrievepassword, rp and resetpass screens redirect to the login page
  and allow_password_reset refuses resets – all unless the fallback link
  is active.
- The login stylesheet is also loaded when only the form is hidden
  (e.g. broken connection); before, the link and form showed there.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

includes/class-m365-login-button.php

@@ -212,6 +212,9 @@ class M365_Login_Button {
 	 * @return string[]
 	 */
 	public function body_class( $classes ) {
+		if ( $this->should_render() ) {
+			$classes[] = 'm365-login-page';
+		}
 		if ( $this->form_hidden() ) {
 			$classes[] = 'm365-button-only';
 		}
@@ -222,7 +225,8 @@ class M365_Login_Button {
 	 * Enqueues login styles and the small positioning script.
 	 */
 	public function enqueue() {
-		if ( ! $this->should_render() ) {
+		// Also when only the form is hidden (e.g. broken connection): the stylesheet hides the password form and links.
+		if ( ! $this->should_render() && ! $this->form_hidden() ) {
 			return;
 		}
 		wp_enqueue_style( 'm365-login', M365_LOGIN_URL . 'assets/css/login.css', array(), M365_LOGIN_VERSION );