feat(robot): per-game display names from a wide name corpus

Decouple the displayed opponent name from the small pool of durable robot
accounts: the disguised auto-match robot now gets a freshly composed name each
game, stamped on a new game_players.display_name seat snapshot. The snapshot
also captures humans' names, freezing what an opponent sees for the life of a
game (a later rename no longer rewrites past games); readers fall back to the
account's current name for pre-migration rows.

Names come from a wide composed corpus (internal/robot/namevariety.go): Western
locales (EN/DE/ES/IT/FR/PT), native Japanese/Chinese names, a gender-agreed
Russian pool, and human-style handles. Routing keeps Pick's spirit -- a Russian
game draws Cyrillic + <=20% Latin and never a CJK script; an English game the
full corpus -- via robot.PickNamed.

Loosen account.ValidateDisplayName (and the UI mirror) to admit a trailing run
of up to five digits, so "Player2007"-style handles are valid for humans too
and the disguised robot stays indistinguishable.

Migration 00007 adds game_players.display_name (additive, NOT NULL DEFAULT '');
jet regenerated. Docs (ARCHITECTURE 7, FUNCTIONAL + _ru, PLAN, README) updated.

backend/internal/postgres/jet/backend/model/game_players.go

@@ -12,10 +12,11 @@ import (
 )
 
 type GamePlayers struct {
-	GameID    uuid.UUID `sql:"primary_key"`
-	Seat      int16     `sql:"primary_key"`
-	AccountID *uuid.UUID
-	Score     int32
-	HintsUsed int16
-	IsWinner  bool
+	GameID      uuid.UUID `sql:"primary_key"`
+	Seat        int16     `sql:"primary_key"`
+	AccountID   *uuid.UUID
+	Score       int32
+	HintsUsed   int16
+	IsWinner    bool
+	DisplayName string
 }

backend/internal/postgres/jet/backend/table/game_players.go

@@ -17,12 +17,13 @@ type gamePlayersTable struct {
 	postgres.Table
 
 	// Columns
-	GameID    postgres.ColumnString
-	Seat      postgres.ColumnInteger
-	AccountID postgres.ColumnString
-	Score     postgres.ColumnInteger
-	HintsUsed postgres.ColumnInteger
-	IsWinner  postgres.ColumnBool
+	GameID      postgres.ColumnString
+	Seat        postgres.ColumnInteger
+	AccountID   postgres.ColumnString
+	Score       postgres.ColumnInteger
+	HintsUsed   postgres.ColumnInteger
+	IsWinner    postgres.ColumnBool
+	DisplayName postgres.ColumnString
 
 	AllColumns     postgres.ColumnList
 	MutableColumns postgres.ColumnList
@@ -64,27 +65,29 @@ func newGamePlayersTable(schemaName, tableName, alias string) *GamePlayersTable
 
 func newGamePlayersTableImpl(schemaName, tableName, alias string) gamePlayersTable {
 	var (
-		GameIDColumn    = postgres.StringColumn("game_id")
-		SeatColumn      = postgres.IntegerColumn("seat")
-		AccountIDColumn = postgres.StringColumn("account_id")
-		ScoreColumn     = postgres.IntegerColumn("score")
-		HintsUsedColumn = postgres.IntegerColumn("hints_used")
-		IsWinnerColumn  = postgres.BoolColumn("is_winner")
-		allColumns      = postgres.ColumnList{GameIDColumn, SeatColumn, AccountIDColumn, ScoreColumn, HintsUsedColumn, IsWinnerColumn}
-		mutableColumns  = postgres.ColumnList{AccountIDColumn, ScoreColumn, HintsUsedColumn, IsWinnerColumn}
-		defaultColumns  = postgres.ColumnList{ScoreColumn, HintsUsedColumn, IsWinnerColumn}
+		GameIDColumn      = postgres.StringColumn("game_id")
+		SeatColumn        = postgres.IntegerColumn("seat")
+		AccountIDColumn   = postgres.StringColumn("account_id")
+		ScoreColumn       = postgres.IntegerColumn("score")
+		HintsUsedColumn   = postgres.IntegerColumn("hints_used")
+		IsWinnerColumn    = postgres.BoolColumn("is_winner")
+		DisplayNameColumn = postgres.StringColumn("display_name")
+		allColumns        = postgres.ColumnList{GameIDColumn, SeatColumn, AccountIDColumn, ScoreColumn, HintsUsedColumn, IsWinnerColumn, DisplayNameColumn}
+		mutableColumns    = postgres.ColumnList{AccountIDColumn, ScoreColumn, HintsUsedColumn, IsWinnerColumn, DisplayNameColumn}
+		defaultColumns    = postgres.ColumnList{ScoreColumn, HintsUsedColumn, IsWinnerColumn, DisplayNameColumn}
 	)
 
 	return gamePlayersTable{
 		Table: postgres.NewTable(schemaName, tableName, alias, allColumns...),
 
 		//Columns
-		GameID:    GameIDColumn,
-		Seat:      SeatColumn,
-		AccountID: AccountIDColumn,
-		Score:     ScoreColumn,
-		HintsUsed: HintsUsedColumn,
-		IsWinner:  IsWinnerColumn,
+		GameID:      GameIDColumn,
+		Seat:        SeatColumn,
+		AccountID:   AccountIDColumn,
+		Score:       ScoreColumn,
+		HintsUsed:   HintsUsedColumn,
+		IsWinner:    IsWinnerColumn,
+		DisplayName: DisplayNameColumn,
 
 		AllColumns:     allColumns,
 		MutableColumns: mutableColumns,