feat(ui): one-tap confirm deeplink screen + client language

Add the /confirm/<token> SPA route and Confirm screen: a prefetch-safe button
POSTs the token via a new confirmEmailLink RPC (client/transport/mock/codec +
ConfirmLinkResult model). A login adopts the minted session and enters the app; a
link shows confirmed / merge-in-the-app; an invalid or expired token asks for a new
code. Exempt /confirm from the no-session /login redirect. Forward the client
locale on the email request (authEmailRequest gains language → app.locale) so a
fresh web login email is localised. Handle the new 'profile' live-event sub-kind by
re-fetching the profile, so a link confirmed in another browser reflects in-app at
once. i18n en+ru.

ui/src/App.svelte

@@ -15,6 +15,7 @@
   import NewGame from './screens/NewGame.svelte';
   import SettingsHub from './screens/SettingsHub.svelte';
   import Stats from './screens/Stats.svelte';
+  import Confirm from './screens/Confirm.svelte';
   import Game from './game/Game.svelte';
   import CommsHub from './game/CommsHub.svelte';
   import Feedback from './screens/Feedback.svelte';
@@ -110,6 +111,8 @@
           <Feedback />
         {:else if router.route.name === 'stats'}
           <Stats />
+        {:else if router.route.name === 'confirm'}
+          <Confirm token={router.route.params.token} />
         {:else}
           <Lobby />
         {/if}