docs+test(email): document the confirm deeplink + wire-contract tests

Document the one-tap confirm deeplink in ARCHITECTURE (§4 the login magic-link /
link confirm+profile-refresh, prefetch-safe token) and the new notify 'profile'
sub-kind (§10), and add the one-tap link to the FUNCTIONAL email story (+ru). Add
codec round-trip assertions for the EmailRequest language field and
encodeEmailConfirmLink (the mock e2e bypasses the codec).

docs/FUNCTIONAL.md

@@ -66,7 +66,10 @@ client's light/dark scheme, and the layout clears the VK mobile home bar. The sa
 is provisioned on the first request but only becomes a durable account once the code
 is confirmed, so an abandoned, never-confirmed attempt is cleaned up and its address
 freed. Sends are rate-limited (a short cooldown between codes and a small hourly cap
-per address), so a mistyped address or an impatient tap cannot flood an inbox.
+per address), so a mistyped address or an impatient tap cannot flood an inbox. The email
+also carries a **one-tap link** that confirms the address — or signs the player straight
+in — in a single tap; opening it in another browser reflects in the app at once, and a
+mail scanner that merely fetches the link never triggers it (it acts only on a button press).
 Telegram runs a **single bot**: every player uses
 the same bot, and all of its chat and out-of-app notifications are written in the
 player's own **interface language** (en/ru). A separate optional **promo bot** can run alongside the