Stage 8: UI social/account/history surfaces

Wire the deferred Stage 7 surfaces end-to-end (UI -> gateway transcode ->
backend REST -> existing domain services): friends (incl. one-time friend
codes), per-user blocks, friend-game invitations, profile editing + email
binding, the statistics screen, and the in-game history + GCG export.

Friends gain two add paths (interview decision, a deliberate plan change):
one-time 6-digit codes (friend_codes table, 12h TTL, single-use, rate-limited
redeem); and play-gated requests (shared game required) where an explicit
decline is permanent, an ignored request lapses after 30 days, and a code
bypasses a decline. Migration 00006 widens friendships_status_chk and adds
friend_codes.

Lobby notification badge is poll + push: a new generic `notify` event drives
it live; the client polls on open/focus. Language stays a single Settings
control that writes through to the durable account's preferred_language. GCG
export is finished-only (game.ErrGameActive) and shares/downloads the .gcg file.

Tests: backend unit + inttest (friend gate/decline/code, ListInvitations,
GetStats, GCG gate), gateway transcode round-trips + notify constructor, UI
vitest (codecs, win-rate, share choice) + Playwright social specs. Docs: PLAN
(Stage 8 done + refinements + TODO-5), ARCHITECTURE, FUNCTIONAL(+ru), UI_DESIGN,
TESTING, module READMEs.

ui/src/lib/client.ts

@@ -5,18 +5,25 @@
 // message.
 
 import type {
+  AccountRef,
   ChatMessage,
   EvalResult,
+  FriendCode,
   GameList,
   GameView,
+  GcgExport,
   History,
   HintResult,
+  Invitation,
+  InvitationSettings,
   MatchResult,
   MoveResult,
   Profile,
+  ProfileUpdate,
   PushEvent,
   Session,
   StateView,
+  Stats,
   Tile,
   Variant,
   WordCheckResult,
@@ -74,6 +81,35 @@ export interface GatewayClient {
   chatList(gameId: string): Promise<ChatMessage[]>;
   nudge(gameId: string): Promise<ChatMessage>;
 
+  // --- friends (Stage 8) ---
+  friendsList(): Promise<AccountRef[]>;
+  friendsIncoming(): Promise<AccountRef[]>;
+  friendRequest(accountId: string): Promise<void>;
+  friendRespond(requesterId: string, accept: boolean): Promise<void>;
+  friendCancel(accountId: string): Promise<void>;
+  unfriend(accountId: string): Promise<void>;
+  friendCodeIssue(): Promise<FriendCode>;
+  friendCodeRedeem(code: string): Promise<AccountRef>;
+
+  // --- blocks (Stage 8) ---
+  blocksList(): Promise<AccountRef[]>;
+  block(accountId: string): Promise<void>;
+  unblock(accountId: string): Promise<void>;
+
+  // --- invitations (Stage 8) ---
+  invitationsList(): Promise<Invitation[]>;
+  invitationCreate(inviteeIds: string[], settings: InvitationSettings): Promise<Invitation>;
+  invitationAccept(invitationId: string): Promise<Invitation>;
+  invitationDecline(invitationId: string): Promise<Invitation>;
+  invitationCancel(invitationId: string): Promise<void>;
+
+  // --- profile / stats / history (Stage 8) ---
+  profileUpdate(p: ProfileUpdate): Promise<Profile>;
+  emailBindRequest(email: string): Promise<void>;
+  emailBindConfirm(email: string, code: string): Promise<Profile>;
+  statsGet(): Promise<Stats>;
+  exportGcg(gameId: string): Promise<GcgExport>;
+
   // --- live stream ---
   subscribe(onEvent: (e: PushEvent) => void, onError?: (err: unknown) => void): Unsubscribe;