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/model.ts

@@ -100,12 +100,84 @@ export interface Profile {
   displayName: string;
   preferredLanguage: string;
   timeZone: string;
+  /** "HH:MM" daily away-window bounds, in timeZone. */
+  awayStart: string;
+  awayEnd: string;
   hintBalance: number;
   blockChat: boolean;
   blockFriendRequests: boolean;
   isGuest: boolean;
 }
 
+/** The full editable profile sent to profileUpdate (overwrites every field). */
+export interface ProfileUpdate {
+  displayName: string;
+  preferredLanguage: string;
+  timeZone: string;
+  awayStart: string;
+  awayEnd: string;
+  blockChat: boolean;
+  blockFriendRequests: boolean;
+}
+
+/** A referenced account with its display name (friend, blocked user, invitee). */
+export interface AccountRef {
+  accountId: string;
+  displayName: string;
+}
+
+/** A freshly issued one-time friend code (the plaintext is returned once). */
+export interface FriendCode {
+  code: string;
+  expiresAtUnix: number;
+}
+
+/** A durable account's lifetime statistics. */
+export interface Stats {
+  wins: number;
+  losses: number;
+  draws: number;
+  maxGamePoints: number;
+  maxWordPoints: number;
+}
+
+/** Settings the inviter chooses for a friend game. */
+export interface InvitationSettings {
+  variant: Variant;
+  turnTimeoutSecs: number;
+  hintsAllowed: boolean;
+  hintsPerPlayer: number;
+  dropoutTiles: 'remove' | 'return';
+}
+
+export interface InvitationInvitee {
+  accountId: string;
+  displayName: string;
+  seat: number;
+  response: 'pending' | 'accepted' | 'declined' | string;
+}
+
+export interface Invitation {
+  id: string;
+  inviter: AccountRef;
+  invitees: InvitationInvitee[];
+  variant: Variant;
+  turnTimeoutSecs: number;
+  hintsAllowed: boolean;
+  hintsPerPlayer: number;
+  dropoutTiles: string;
+  status: string;
+  gameId: string;
+  expiresAtUnix: number;
+}
+
+/** A finished game's GCG transcript for download/share. */
+export interface GcgExport {
+  gameId: string;
+  filename: string;
+  content: string;
+}
+
 export interface Session {
   token: string;
   userId: string;
@@ -134,4 +206,5 @@ export type PushEvent =
   | { kind: 'chat_message'; message: ChatMessage }
   | { kind: 'nudge'; gameId: string; fromUserId: string }
   | { kind: 'match_found'; gameId: string }
+  | { kind: 'notify'; sub: string }
   | { kind: 'heartbeat' };