feat(ui): single-word rule indicators + auto-match select redesign

Surface the per-game "single word" rule to the client and refine the
random-opponent New Game screen.

- Wire: thread multiple_words_per_turn into the GameView and Invitation
  FlatBuffers tables (Go + TS regenerated), through pkg/wire builders and both
  the backend push-event and gateway REST paths.
- In-game indicators (single-word games only): a small 1 in the status bar's
  score-preview slot (yields to the live preview) and a centred "One word per
  turn" label in the history-drawer header. Standard games show neither.
- Invitation card gains a "One word per turn" line for single-word invitations.
- Auto-match redesign: variant plaques are mutually-exclusive selects (highlight
  on tap, no longer enqueue); a lone offered variant is pre-selected; a bottom
  "Start game" button (disabled until a variant is chosen) confirms. The rule
  toggle appears once a Russian variant is selected.
- Tests: e2e for the new auto flow and the in-game indicator (mock g3 is a
  single-word game); mock/data + fixtures carry the new field. Docs: UI_DESIGN.

ui/src/gen/fbs/scrabblefb/game-view.ts

@@ -66,35 +66,40 @@ turnTimeoutSecs():number {
   return offset ? this.bb!.readInt32(this.bb_pos + offset) : 0;
 }
 
-moveCount():number {
+multipleWordsPerTurn():boolean {
   const offset = this.bb!.__offset(this.bb_pos, 18);
+  return offset ? !!this.bb!.readInt8(this.bb_pos + offset) : false;
+}
+
+moveCount():number {
+  const offset = this.bb!.__offset(this.bb_pos, 20);
   return offset ? this.bb!.readInt32(this.bb_pos + offset) : 0;
 }
 
 endReason():string|null
 endReason(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
 endReason(optionalEncoding?:any):string|Uint8Array|null {
-  const offset = this.bb!.__offset(this.bb_pos, 20);
+  const offset = this.bb!.__offset(this.bb_pos, 22);
   return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
 }
 
 seats(index: number, obj?:SeatView):SeatView|null {
-  const offset = this.bb!.__offset(this.bb_pos, 22);
+  const offset = this.bb!.__offset(this.bb_pos, 24);
   return offset ? (obj || new SeatView()).__init(this.bb!.__indirect(this.bb!.__vector(this.bb_pos + offset) + index * 4), this.bb!) : null;
 }
 
 seatsLength():number {
-  const offset = this.bb!.__offset(this.bb_pos, 22);
+  const offset = this.bb!.__offset(this.bb_pos, 24);
   return offset ? this.bb!.__vector_len(this.bb_pos + offset) : 0;
 }
 
 lastActivityUnix():bigint {
-  const offset = this.bb!.__offset(this.bb_pos, 24);
+  const offset = this.bb!.__offset(this.bb_pos, 26);
   return offset ? this.bb!.readInt64(this.bb_pos + offset) : BigInt('0');
 }
 
 static startGameView(builder:flatbuffers.Builder) {
-  builder.startObject(11);
+  builder.startObject(12);
 }
 
 static addId(builder:flatbuffers.Builder, idOffset:flatbuffers.Offset) {
@@ -125,16 +130,20 @@ static addTurnTimeoutSecs(builder:flatbuffers.Builder, turnTimeoutSecs:number) {
   builder.addFieldInt32(6, turnTimeoutSecs, 0);
 }
 
+static addMultipleWordsPerTurn(builder:flatbuffers.Builder, multipleWordsPerTurn:boolean) {
+  builder.addFieldInt8(7, +multipleWordsPerTurn, +false);
+}
+
 static addMoveCount(builder:flatbuffers.Builder, moveCount:number) {
-  builder.addFieldInt32(7, moveCount, 0);
+  builder.addFieldInt32(8, moveCount, 0);
 }
 
 static addEndReason(builder:flatbuffers.Builder, endReasonOffset:flatbuffers.Offset) {
-  builder.addFieldOffset(8, endReasonOffset, 0);
+  builder.addFieldOffset(9, endReasonOffset, 0);
 }
 
 static addSeats(builder:flatbuffers.Builder, seatsOffset:flatbuffers.Offset) {
-  builder.addFieldOffset(9, seatsOffset, 0);
+  builder.addFieldOffset(10, seatsOffset, 0);
 }
 
 static createSeatsVector(builder:flatbuffers.Builder, data:flatbuffers.Offset[]):flatbuffers.Offset {
@@ -150,7 +159,7 @@ static startSeatsVector(builder:flatbuffers.Builder, numElems:number) {
 }
 
 static addLastActivityUnix(builder:flatbuffers.Builder, lastActivityUnix:bigint) {
-  builder.addFieldInt64(10, lastActivityUnix, BigInt('0'));
+  builder.addFieldInt64(11, lastActivityUnix, BigInt('0'));
 }
 
 static endGameView(builder:flatbuffers.Builder):flatbuffers.Offset {
@@ -158,7 +167,7 @@ static endGameView(builder:flatbuffers.Builder):flatbuffers.Offset {
   return offset;
 }
 
-static createGameView(builder:flatbuffers.Builder, idOffset:flatbuffers.Offset, variantOffset:flatbuffers.Offset, dictVersionOffset:flatbuffers.Offset, statusOffset:flatbuffers.Offset, players:number, toMove:number, turnTimeoutSecs:number, moveCount:number, endReasonOffset:flatbuffers.Offset, seatsOffset:flatbuffers.Offset, lastActivityUnix:bigint):flatbuffers.Offset {
+static createGameView(builder:flatbuffers.Builder, idOffset:flatbuffers.Offset, variantOffset:flatbuffers.Offset, dictVersionOffset:flatbuffers.Offset, statusOffset:flatbuffers.Offset, players:number, toMove:number, turnTimeoutSecs:number, multipleWordsPerTurn:boolean, moveCount:number, endReasonOffset:flatbuffers.Offset, seatsOffset:flatbuffers.Offset, lastActivityUnix:bigint):flatbuffers.Offset {
   GameView.startGameView(builder);
   GameView.addId(builder, idOffset);
   GameView.addVariant(builder, variantOffset);
@@ -167,6 +176,7 @@ static createGameView(builder:flatbuffers.Builder, idOffset:flatbuffers.Offset,
   GameView.addPlayers(builder, players);
   GameView.addToMove(builder, toMove);
   GameView.addTurnTimeoutSecs(builder, turnTimeoutSecs);
+  GameView.addMultipleWordsPerTurn(builder, multipleWordsPerTurn);
   GameView.addMoveCount(builder, moveCount);
   GameView.addEndReason(builder, endReasonOffset);
   GameView.addSeats(builder, seatsOffset);

ui/src/gen/fbs/scrabblefb/invitation.ts

@@ -68,34 +68,39 @@ hintsPerPlayer():number {
   return offset ? this.bb!.readInt32(this.bb_pos + offset) : 0;
 }
 
+multipleWordsPerTurn():boolean {
+  const offset = this.bb!.__offset(this.bb_pos, 18);
+  return offset ? !!this.bb!.readInt8(this.bb_pos + offset) : false;
+}
+
 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);
+  const offset = this.bb!.__offset(this.bb_pos, 20);
   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);
+  const offset = this.bb!.__offset(this.bb_pos, 22);
   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);
+  const offset = this.bb!.__offset(this.bb_pos, 24);
   return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
 }
 
 expiresAtUnix():bigint {
-  const offset = this.bb!.__offset(this.bb_pos, 24);
+  const offset = this.bb!.__offset(this.bb_pos, 26);
   return offset ? this.bb!.readInt64(this.bb_pos + offset) : BigInt('0');
 }
 
 static startInvitation(builder:flatbuffers.Builder) {
-  builder.startObject(11);
+  builder.startObject(12);
 }
 
 static addId(builder:flatbuffers.Builder, idOffset:flatbuffers.Offset) {
@@ -138,20 +143,24 @@ static addHintsPerPlayer(builder:flatbuffers.Builder, hintsPerPlayer:number) {
   builder.addFieldInt32(6, hintsPerPlayer, 0);
 }
 
+static addMultipleWordsPerTurn(builder:flatbuffers.Builder, multipleWordsPerTurn:boolean) {
+  builder.addFieldInt8(7, +multipleWordsPerTurn, +false);
+}
+
 static addDropoutTiles(builder:flatbuffers.Builder, dropoutTilesOffset:flatbuffers.Offset) {
-  builder.addFieldOffset(7, dropoutTilesOffset, 0);
+  builder.addFieldOffset(8, dropoutTilesOffset, 0);
 }
 
 static addStatus(builder:flatbuffers.Builder, statusOffset:flatbuffers.Offset) {
-  builder.addFieldOffset(8, statusOffset, 0);
+  builder.addFieldOffset(9, statusOffset, 0);
 }
 
 static addGameId(builder:flatbuffers.Builder, gameIdOffset:flatbuffers.Offset) {
-  builder.addFieldOffset(9, gameIdOffset, 0);
+  builder.addFieldOffset(10, gameIdOffset, 0);
 }
 
 static addExpiresAtUnix(builder:flatbuffers.Builder, expiresAtUnix:bigint) {
-  builder.addFieldInt64(10, expiresAtUnix, BigInt('0'));
+  builder.addFieldInt64(11, expiresAtUnix, BigInt('0'));
 }
 
 static endInvitation(builder:flatbuffers.Builder):flatbuffers.Offset {