Room codes also dodge orphaned files on disk

makeRoomCode checked only the in-memory map, which covers every live
and restored room — but a file that failed to restore stays on disk
with no map entry, and a new room taking its code would append a
second game into the orphaned file, corrupting both. The generator
now rerolls on disk presence too.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/server/src/rooms.ts

@@ -15,7 +15,7 @@ import {
   type GameView,
   type PlayerId,
 } from "@wizwar/engine";
-import { appendLine, ensureDataDir, readAllRooms, type RoomLine } from "./store";
+import { appendLine, ensureDataDir, readAllRooms, roomFileExists, type RoomLine } from "./store";
 import { recordRoom } from "./stats";
 
 export interface LoggedCommand {
@@ -72,7 +72,9 @@ function makeRoomCode(): string {
   for (let i = 0; i < 4; i++) {
     code += ROOM_CODE_ALPHABET[randomInt(ROOM_CODE_ALPHABET.length)];
   }
-  return rooms.has(code) ? makeRoomCode() : code;
+  // The disk check covers rooms that exist on file but failed to restore —
+  // reusing such a code would append a new game into the orphaned file.
+  return rooms.has(code) || roomFileExists(code) ? makeRoomCode() : code;
 }
 
 export function roomCount(): number {