Translation gaps in 2.4.0: dates, Element Plus locale, split sentences #430

Thanks for routing all admin texts through TransStrings.php. Every $t() lookup in the app bundle has a map entry, which made a complete German translation possible. A few things remain that a translation cannot reach (FluentSMTP 2.4.0, WordPress 7.1, site language de_DE and de_DE_formal):

1. Dates ignore the site language. The log list, "Recent activity" and the log details use $dateFormat(…, "DD MMM YYYY LT"), the sending chart uses format("MMM D"). dayjs has no locale loaded, so a German site shows "16 Sep 2026 6:17 PM" and "Sep 11". Loading the dayjs locale that matches the WordPress locale (or formatting with Intl.DateTimeFormat) would fix it. For German we currently bridge this with a small helper plugin, but every other language is still affected.
2. Element Plus has no locale. The log pagination shows "Total 27" and "10/page", and the date range picker shows English weekday and month names. Passing the matching Element Plus locale to the app would translate these.
3. 'activate ' is in the translation catalogue. It is the command sent to @fluentsmtp_bot. If a translator translates it, the bot presumably no longer recognises it. Please keep it out of __().
4. Sentences split into fragments ("Sign in to" + link + "and add your sending domain.", "Add " + URL + " to the " + …, "Simulation is turned on by " + constant + " in your PHP code, …") force a word order that does not work in German. One string with placeholders (sprintf, or %s resolved in the app) would translate cleanly.
5. Near duplicates: "learn why it's free" / "Learn why it's free" and "failed" / "Failed" are the same label twice.