Tidy admin settings cards

Offer every shipped locale as the server default language, move the app
log refresh out of the header status slot, let filter selects fill their
grid cells, name the coverage table as a focusable region, hide the
legacy-key badge when only one key exists, keep the encryption cards
still while they load, and stop repeating the page title in card titles.

src/components/admin/module-availability-section.tsx

@@ -95,11 +95,7 @@ export function ModuleAvailabilitySection() {
 
   return (
     <SettingsCard>
-      <SettingsCardHeader
-        icon={ToggleLeft}
-        title={t("admin.modules.title")}
-        description={t("admin.modules.description")}
-      />
+      <SettingsCardHeader icon={ToggleLeft} title={t("admin.modules.title")} />
       <p className="text-sm">{t("admin.modules.detail")}</p>
 
       <div className="space-y-4">
@@ -133,7 +129,7 @@ export function ModuleAvailabilitySection() {
                     href="/admin/coach"
                     className="text-primary text-xs underline-offset-4 hover:underline"
                   >
-                    {t("admin.assistant.title")}
+                    {t("admin.section.coach.title")}
                   </Link>
                 </div>
               );