Add DE/FR/ES support across Chrome, Edge and Firefox builds: new _locales message files for de, fr, es. Include dayjs locale bundles (de.js, fr.js, es.js) and load them in popup.html. Update i18n.js to register new languages and labels, update oper.js to apply the corresponding dayjs locale (including auto-detection), add language buttons to the popup UI, bump manifest version, and record the change in change.log.
Add a GitHub Actions workflow (package-extensions.yml) to build and upload Chrome/Firefox packages (store and offline artifacts) on manual trigger or when pushing v* tags. Update README with packaging instructions. Reorganize extension sources into chrome/ and firefox/ directories, add Firefox-specific files (manifest, locales, assets, CSS, LICENSE), and bump Chrome manifest version to 2026.04.23. Also modify js/oper.js (moved to chrome/js) to improve proportional editor resizing: add drag-to-resize, scale clamping/persistence (localStorage + chrome.storage.sync), pointer event handlers, and max-scale computation.
jonny