gsmi 2.0.0-rc1

First release candidate for gsmi 2.0.0. Changes since 2.0.0-beta2:

• Drupal 12 compatibility — automated fixes from the Project Update Bot (#3598796); core requirement is now ^10.4 || ^11 || ^12.
• Multilanguage support — images are generated and cached per translation, with langcode-suffixed filenames, per-translation cache entries, redirects for stale derivatives, and a preview-language selector on the settings form.
• Shipped interface translations — German and French, imported automatically on install/update.
• No more duplicate entities — saved filenames encode image style, field and language; repeated generate calls reuse the existing file and media entity instead of creating duplicates.
• Accessibility hint — when the image media type requires alternative text, saving to media warns with an edit link so the empty alt gets filled in.
• Project logo for the Project Browser and project page.
• Code quality — all GitLab CI checks (phpunit, phpstan, phpcs, cspell, stylelint, eslint) are now enforced and green; hook implementations use constructor injection.

Disclaimer: Development was assisted by AI (Claude); all changes were reviewed and tested by the maintainer.