Fix: FS_Api::clear_force_http_flag() dereferences a null $_options.

Freemius SDK bug (present through 2.13.1 / master as of 2026-06). The static
method clear_force_http_flag() calls self::$_options->unset_option() without
first calling self::_init() to populate $_options, unlike its sibling
clear_cache() which inits first. When clear_connectivity_info()
(class-freemius.php) invokes it before any FS_Api::_init() has run -- e.g. a
connectivity test under WP-CLI / WP-Cron where $_SERVER['HTTP_HOST'] is unset --
$_options is null and PHP fatals:

    Call to a member function unset_option() on null  (class-fs-api.php:593)

Fix mirrors clear_cache() by calling self::_init() first. Remove once an
upstream Freemius SDK release includes the fix.

--- a/src/Library/freemius/includes/class-fs-api.php
+++ b/src/Library/freemius/includes/class-fs-api.php
@@ -590,6 +590,8 @@
          * @since  2.5.4
          */
         static function clear_force_http_flag() {
+            self::_init();
+
             self::$_options->unset_option( 'api_force_http' );
         }