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/codec.ts

@@ -179,27 +179,33 @@ export function encodeChatPost(gameId: string, body: string): Uint8Array {
   return finish(b, fb.ChatPostRequest.endChatPostRequest(b));
 }
 
-export function encodeTelegramLogin(initData: string): Uint8Array {
+export function encodeTelegramLogin(initData: string, browserTz: string): Uint8Array {
   const b = new Builder(512);
   const d = b.createString(initData);
+  const tz = b.createString(browserTz);
   fb.TelegramLoginRequest.startTelegramLoginRequest(b);
   fb.TelegramLoginRequest.addInitData(b, d);
+  fb.TelegramLoginRequest.addBrowserTz(b, tz);
   return finish(b, fb.TelegramLoginRequest.endTelegramLoginRequest(b));
 }
 
-export function encodeGuestLogin(locale: string): Uint8Array {
+export function encodeGuestLogin(locale: string, browserTz: string): Uint8Array {
   const b = new Builder(64);
   const l = b.createString(locale);
+  const tz = b.createString(browserTz);
   fb.GuestLoginRequest.startGuestLoginRequest(b);
   fb.GuestLoginRequest.addLocale(b, l);
+  fb.GuestLoginRequest.addBrowserTz(b, tz);
   return finish(b, fb.GuestLoginRequest.endGuestLoginRequest(b));
 }
 
-export function encodeEmailRequest(email: string): Uint8Array {
+export function encodeEmailRequest(email: string, browserTz: string): Uint8Array {
   const b = new Builder(128);
   const e = b.createString(email);
+  const tz = b.createString(browserTz);
   fb.EmailRequestRequest.startEmailRequestRequest(b);
   fb.EmailRequestRequest.addEmail(b, e);
+  fb.EmailRequestRequest.addBrowserTz(b, tz);
   return finish(b, fb.EmailRequestRequest.endEmailRequestRequest(b));
 }