v1.3.1 — Live auto-update confirmation

No functional changes. This release confirms the v1.3.0 auto-update
mechanism actually works end-to-end on a live site: v1.3.0 was
manually installed once, and this release should now appear as a
normal "Update available" notice in wp-admin with zero further
manual steps.

Also bumps "Tested up to" to 6.8, clearing WordPress's cosmetic
"not tested with your current version" advisory (the plugin only
uses long-stable core APIs with no version-specific behavior).

v1.3.0 — Dedicated repo, native auto-updates

First release from this dedicated repo. Moved out of the private Kinash/WCAP monorepo so installing/updating this plugin never requires anything beyond wp-admin access on any client site — no GitHub token, no wp-config.php edit, no cPanel/FTP access. Also adds the GET /rankmath/{post_id}/score endpoint (from v1.1.0) and fixes a stale README example that referenced a field (schema_type) the plugin has never actually written.