Security hardening: bot keys, Bulk Generate, add-on updates and llms.txt

Shipped in Pro 2.0.10, SEOBetter Agent 0.4.1, Keyword Research 0.9.2 and free 1.0.117: bot keys act as an Editor or Author and never save raw HTML, with a daily delete allowance; Bulk Generate batches are private to their creator and auto-publish only for users who can publish; add-on updates require a published checksum; password-protected posts stay out of llms.txt, llms-full.txt and schema; link checks re-check redirects. Details: https://help.seobetter.com/board/mindiamaiweb-d7c367/kb/656