feat(account): seed the time zone from the client's detected offset at creation

A new account's time_zone defaulted to 'UTC' until the player saved a profile, so the
robot's sleep window and the turn-timeout away-window sweeper — both anchored to the
account zone via account.ResolveZone — ran on UTC for every fresh player, skewing
robot-game timing until a manual Settings save. Seed the zone at creation instead, from
the client's detected "±HH:MM" offset.

- Carry browser_tz on the three account-creating auth requests (TelegramLoginRequest,
  GuestLoginRequest, EmailRequestRequest — the email account is provisioned at the
  code-request step, not at login) through the fbs envelope (+ Go/TS codegen), the
  gateway transcode + backend client, and the backend auth handlers into
  ProvisionTelegram / ProvisionGuest / ProvisionEmail.
- create() now writes time_zone explicitly: the validated detected offset, or 'UTC'
  (equal to the column default) when absent or malformed — deterministic, never guessed.
  The column is already NOT NULL DEFAULT 'UTC', so no migration is needed and existing
  accounts keep 'UTC'. An existing account is never overwritten on re-login.
- A detected zero offset is stored as "+00:00" (the zone is known and equals UTC),
  distinct from the "UTC" default that means "unknown" — which the feedback console's
  three-zone Filed display already reflects.
- Guard the guest handler against an empty payload (the bootstrap historically carried
  none) so it degrades to no-seed rather than panicking in GetRootAs*.
- Tests: zone seeding across Telegram/guest/email plus the "+00:00"/malformed/empty
  cases and the not-overwrite rule; codec round-trip for the three auth encoders.
  ARCHITECTURE + FUNCTIONAL(+ru) updated.

ui/src/lib/transport.ts

@@ -63,13 +63,13 @@ export function createTransport(baseUrl: string): GatewayClient {
     },
 
     async authTelegram(initData) {
-      return codec.decodeSession(await exec('auth.telegram', codec.encodeTelegramLogin(initData)));
+      return codec.decodeSession(await exec('auth.telegram', codec.encodeTelegramLogin(initData, browserOffset())));
     },
     async authGuest(locale) {
-      return codec.decodeSession(await exec('auth.guest', codec.encodeGuestLogin(locale ?? '')));
+      return codec.decodeSession(await exec('auth.guest', codec.encodeGuestLogin(locale ?? '', browserOffset())));
     },
     async authEmailRequest(email) {
-      await exec('auth.email.request', codec.encodeEmailRequest(email));
+      await exec('auth.email.request', codec.encodeEmailRequest(email, browserOffset()));
     },
     async authEmailLogin(email, code) {
       return codec.decodeSession(await exec('auth.email.login', codec.encodeEmailLogin(email, code)));