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).

docs/ARCHITECTURE.md

@@ -244,8 +244,9 @@ arrive from a platform rather than completing a mandatory registration).
   256-bit token stored only as its SHA-256, 12-hour TTL): a login mints a session in the
   browser that opens it (magic-link), a link confirms the identity and emits a `notify`
   profile-refresh to the in-app session, and a would-be merge is deferred to the
-  interactive flow. The confirm page is prefetch-safe — it confirms only on a button
-  press, so a mail scanner's GET does not consume the single-use token. An
+  interactive flow. The confirm runs on load; 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. An
   **email-login** account is created flagged `is_guest` and stays reapable until the
   code is confirmed — so an abandoned, never-confirmed login frees its reserved
   address — with confirming clearing the flag. Accounts and identities use