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/gen/fbs/scrabblefb/invitation.ts

@@ -0,0 +1,162 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+import * as flatbuffers from 'flatbuffers';
+
+import { AccountRef } from '../scrabblefb/account-ref.js';
+import { InvitationInvitee } from '../scrabblefb/invitation-invitee.js';
+
+
+export class Invitation {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):Invitation {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsInvitation(bb:flatbuffers.ByteBuffer, obj?:Invitation):Invitation {
+  return (obj || new Invitation()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsInvitation(bb:flatbuffers.ByteBuffer, obj?:Invitation):Invitation {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new Invitation()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+id():string|null
+id(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+id(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+inviter(obj?:AccountRef):AccountRef|null {
+  const offset = this.bb!.__offset(this.bb_pos, 6);
+  return offset ? (obj || new AccountRef()).__init(this.bb!.__indirect(this.bb_pos + offset), this.bb!) : null;
+}
+
+invitees(index: number, obj?:InvitationInvitee):InvitationInvitee|null {
+  const offset = this.bb!.__offset(this.bb_pos, 8);
+  return offset ? (obj || new InvitationInvitee()).__init(this.bb!.__indirect(this.bb!.__vector(this.bb_pos + offset) + index * 4), this.bb!) : null;
+}
+
+inviteesLength():number {
+  const offset = this.bb!.__offset(this.bb_pos, 8);
+  return offset ? this.bb!.__vector_len(this.bb_pos + offset) : 0;
+}
+
+variant():string|null
+variant(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+variant(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 10);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+turnTimeoutSecs():number {
+  const offset = this.bb!.__offset(this.bb_pos, 12);
+  return offset ? this.bb!.readInt32(this.bb_pos + offset) : 0;
+}
+
+hintsAllowed():boolean {
+  const offset = this.bb!.__offset(this.bb_pos, 14);
+  return offset ? !!this.bb!.readInt8(this.bb_pos + offset) : false;
+}
+
+hintsPerPlayer():number {
+  const offset = this.bb!.__offset(this.bb_pos, 16);
+  return offset ? this.bb!.readInt32(this.bb_pos + offset) : 0;
+}
+
+dropoutTiles():string|null
+dropoutTiles(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+dropoutTiles(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 18);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+status():string|null
+status(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+status(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 20);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+gameId():string|null
+gameId(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+gameId(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 22);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
+expiresAtUnix():bigint {
+  const offset = this.bb!.__offset(this.bb_pos, 24);
+  return offset ? this.bb!.readInt64(this.bb_pos + offset) : BigInt('0');
+}
+
+static startInvitation(builder:flatbuffers.Builder) {
+  builder.startObject(11);
+}
+
+static addId(builder:flatbuffers.Builder, idOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(0, idOffset, 0);
+}
+
+static addInviter(builder:flatbuffers.Builder, inviterOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(1, inviterOffset, 0);
+}
+
+static addInvitees(builder:flatbuffers.Builder, inviteesOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(2, inviteesOffset, 0);
+}
+
+static createInviteesVector(builder:flatbuffers.Builder, data:flatbuffers.Offset[]):flatbuffers.Offset {
+  builder.startVector(4, data.length, 4);
+  for (let i = data.length - 1; i >= 0; i--) {
+    builder.addOffset(data[i]!);
+  }
+  return builder.endVector();
+}
+
+static startInviteesVector(builder:flatbuffers.Builder, numElems:number) {
+  builder.startVector(4, numElems, 4);
+}
+
+static addVariant(builder:flatbuffers.Builder, variantOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(3, variantOffset, 0);
+}
+
+static addTurnTimeoutSecs(builder:flatbuffers.Builder, turnTimeoutSecs:number) {
+  builder.addFieldInt32(4, turnTimeoutSecs, 0);
+}
+
+static addHintsAllowed(builder:flatbuffers.Builder, hintsAllowed:boolean) {
+  builder.addFieldInt8(5, +hintsAllowed, +false);
+}
+
+static addHintsPerPlayer(builder:flatbuffers.Builder, hintsPerPlayer:number) {
+  builder.addFieldInt32(6, hintsPerPlayer, 0);
+}
+
+static addDropoutTiles(builder:flatbuffers.Builder, dropoutTilesOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(7, dropoutTilesOffset, 0);
+}
+
+static addStatus(builder:flatbuffers.Builder, statusOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(8, statusOffset, 0);
+}
+
+static addGameId(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(9, gameIdOffset, 0);
+}
+
+static addExpiresAtUnix(builder:flatbuffers.Builder, expiresAtUnix:bigint) {
+  builder.addFieldInt64(10, expiresAtUnix, BigInt('0'));
+}
+
+static endInvitation(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  return offset;
+}
+
+}