feat(admin): manual account blocking (suspensions)

Operator-driven hard block, the counterpart to the soft high-rate flag: permanent or until a date, with an optional reason chosen from an editable en+ru picklist (snapshotted onto the block). A block forfeits the player's active games (opponent wins, as a resignation) and cancels their open matchmaking games. A backend gate refuses a blocked account on every /api/v1/user/* route except the block-status probe with 403 account_blocked, which threads through the gateway as the Execute result_code; the UI surfaces it as a terminal blocked screen and stops all push/poll. Temporary blocks self-expire; the operator can unblock at any time (lost games stay lost). Sessions are not revoked, so the blocked client can still reach the exempt block-status endpoint.

Backend: migration 00003 (account_suspensions + suspension_reasons) + jet regen; account suspension store; game.ForfeitAllForAccount; requireNotSuspended gate + block-status endpoint; admin console block/unblock + Reasons CRUD. Wire: fbs BlockStatus + account.block_status gateway op. UI: blocked screen, app state, transport/codec, i18n. Docs: ARCHITECTURE, FUNCTIONAL(+ru), PRERELEASE (AB).

backend/internal/game/store.go

@@ -354,6 +354,26 @@ func (s *Store) SharedGameExists(ctx context.Context, a, b uuid.UUID) (bool, err
 	return len(rows) > 0, nil
 }
 
+// DeleteOpenGame removes a game only while it is still open (an auto-match game awaiting an
+// opponent), reporting whether a row was deleted. The starter's lone seat and any draft cascade
+// away with it. It no-ops (false) once the game has filled and become active, so a caller can
+// fall back to resigning the now-active seat. Used to clear a blocked player from matchmaking.
+func (s *Store) DeleteOpenGame(ctx context.Context, gameID uuid.UUID) (bool, error) {
+	stmt := table.Games.DELETE().WHERE(
+		table.Games.GameID.EQ(postgres.UUID(gameID)).
+			AND(table.Games.Status.EQ(postgres.String(StatusOpen))),
+	)
+	res, err := stmt.ExecContext(ctx, s.db)
+	if err != nil {
+		return false, fmt.Errorf("game: delete open game %s: %w", gameID, err)
+	}
+	n, err := res.RowsAffected()
+	if err != nil {
+		return false, fmt.Errorf("game: delete open game rows %s: %w", gameID, err)
+	}
+	return n > 0, nil
+}
+
 // ListGamesForAccount loads every game the account is seated in (active and
 // finished), newest first, each joined with its ordered seats. It backs the lobby's
 // "my games" lists.