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/lib/codec.ts

@@ -31,6 +31,7 @@ import type {
   Invitation,
   InvitationInvitee,
   InvitationSettings,
+  ConfirmLinkResult,
   LinkResult,
   MatchResult,
   MoveRecord,
@@ -212,13 +213,15 @@ export function encodeGuestLogin(locale: string, browserTz: string): Uint8Array
   return finish(b, fb.GuestLoginRequest.endGuestLoginRequest(b));
 }
 
-export function encodeEmailRequest(email: string, browserTz: string): Uint8Array {
+export function encodeEmailRequest(email: string, browserTz: string, language: string): Uint8Array {
   const b = new Builder(128);
   const e = b.createString(email);
   const tz = b.createString(browserTz);
+  const l = b.createString(language);
   fb.EmailRequestRequest.startEmailRequestRequest(b);
   fb.EmailRequestRequest.addEmail(b, e);
   fb.EmailRequestRequest.addBrowserTz(b, tz);
+  fb.EmailRequestRequest.addLanguage(b, l);
   return finish(b, fb.EmailRequestRequest.endEmailRequestRequest(b));
 }
 
@@ -232,6 +235,14 @@ export function encodeEmailLogin(email: string, code: string): Uint8Array {
   return finish(b, fb.EmailLoginRequest.endEmailLoginRequest(b));
 }
 
+export function encodeEmailConfirmLink(token: string): Uint8Array {
+  const b = new Builder(128);
+  const t = b.createString(token);
+  fb.EmailConfirmLinkRequest.startEmailConfirmLinkRequest(b);
+  fb.EmailConfirmLinkRequest.addToken(b, t);
+  return finish(b, fb.EmailConfirmLinkRequest.endEmailConfirmLinkRequest(b));
+}
+
 // --- response decoders ---
 
 function s(v: string | null): string {
@@ -730,6 +741,16 @@ export function decodeLinkResult(buf: Uint8Array): LinkResult {
   };
 }
 
+export function decodeConfirmLinkResult(buf: Uint8Array): ConfirmLinkResult {
+  const r = fb.EmailConfirmLinkResult.getRootAsEmailConfirmLinkResult(new ByteBuffer(buf));
+  const sess = r.session();
+  return {
+    purpose: (s(r.purpose()) || 'link') as ConfirmLinkResult['purpose'],
+    status: (s(r.status()) || 'confirmed') as ConfirmLinkResult['status'],
+    session: sess ? sessionFromTable(sess) : null,
+  };
+}
+
 // --- social decoders ---
 
 function decodeAccountRef(r: fb.AccountRef): AccountRef {