feat(ui): auto-confirm the email deeplink on load

Drop the confirm button: the /confirm screen confirms the token as soon as it
loads. The token rides the URL fragment (never sent to the server), so a plain link
prefetch cannot reach it, and the manual six-digit code is the fallback if an
aggressive scanner runs the page. Update the ARCHITECTURE/FUNCTIONAL wording
accordingly and swap the confirm.prompt/action strings for confirm.busy (en+ru).

ui/src/lib/i18n/en.ts

@@ -36,8 +36,7 @@ export const en = {
   'login.sendCode': 'Send code',
   'login.codePlaceholder': '6-digit code',
   'login.signIn': 'Sign in',
-  'confirm.prompt': 'Confirm your email to finish.',
-  'confirm.action': 'Confirm',
+  'confirm.busy': 'Confirming your email…',
   'confirm.linked': 'Email confirmed.',
   'confirm.merge': 'Almost done — finish the merge in the app.',
   'confirm.close': 'You can close this window and return to the game.',