Round 2 review-compliance fixes.
- Fix: Plugin URI and front-end footer link now resolve (https://plugins.ettic.nl/opentrust); the previous URL returned 404.
- Change: custom post type slugs renamed from eotc_ to ettotc_, a 4+ char prefix that stays within WordPress's 20-char post_type limit (ettic_otc_certification would be 23). Export ZIPs from earlier builds remap to the new slugs automatically on import.
- Housekeeping: regenerated translation template; changelog and upgrade notice added.
Install ZIP attached below. CI and Semgrep green on main.