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/profile.ts

@@ -68,8 +68,22 @@ isGuest():boolean {
   return offset ? !!this.bb!.readInt8(this.bb_pos + offset) : false;
 }
 
+awayStart():string|null
+awayStart(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+awayStart(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;
+}
+
+awayEnd():string|null
+awayEnd(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+awayEnd(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;
+}
+
 static startProfile(builder:flatbuffers.Builder) {
-  builder.startObject(8);
+  builder.startObject(10);
 }
 
 static addUserId(builder:flatbuffers.Builder, userIdOffset:flatbuffers.Offset) {
@@ -104,12 +118,20 @@ static addIsGuest(builder:flatbuffers.Builder, isGuest:boolean) {
   builder.addFieldInt8(7, +isGuest, +false);
 }
 
+static addAwayStart(builder:flatbuffers.Builder, awayStartOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(8, awayStartOffset, 0);
+}
+
+static addAwayEnd(builder:flatbuffers.Builder, awayEndOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(9, awayEndOffset, 0);
+}
+
 static endProfile(builder:flatbuffers.Builder):flatbuffers.Offset {
   const offset = builder.endObject();
   return offset;
 }
 
-static createProfile(builder:flatbuffers.Builder, userIdOffset:flatbuffers.Offset, displayNameOffset:flatbuffers.Offset, preferredLanguageOffset:flatbuffers.Offset, timeZoneOffset:flatbuffers.Offset, hintBalance:number, blockChat:boolean, blockFriendRequests:boolean, isGuest:boolean):flatbuffers.Offset {
+static createProfile(builder:flatbuffers.Builder, userIdOffset:flatbuffers.Offset, displayNameOffset:flatbuffers.Offset, preferredLanguageOffset:flatbuffers.Offset, timeZoneOffset:flatbuffers.Offset, hintBalance:number, blockChat:boolean, blockFriendRequests:boolean, isGuest:boolean, awayStartOffset:flatbuffers.Offset, awayEndOffset:flatbuffers.Offset):flatbuffers.Offset {
   Profile.startProfile(builder);
   Profile.addUserId(builder, userIdOffset);
   Profile.addDisplayName(builder, displayNameOffset);
@@ -119,6 +141,8 @@ static createProfile(builder:flatbuffers.Builder, userIdOffset:flatbuffers.Offse
   Profile.addBlockChat(builder, blockChat);
   Profile.addBlockFriendRequests(builder, blockFriendRequests);
   Profile.addIsGuest(builder, isGuest);
+  Profile.addAwayStart(builder, awayStartOffset);
+  Profile.addAwayEnd(builder, awayEndOffset);
   return Profile.endProfile(builder);
 }
 }