Hide clan tags in public FFA games to prevent teaming (#4000)

## Description:

- Added optional `disableClanTags` to `GameConfig`. When set, the server
strips clan tags from `gameInfo` (lobby broadcasts/HTTP) and
`gameStartInfo` (start payload) before sending to clients. Archive keeps
the originals.
- Enabled `disableClanTags` for public FFA games (both the regular FFA
playlist and special when randomized to FFA). No UI; clients still see
their own clan tag via local input state.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

evan

src/core/Schemas.ts

@@ -253,6 +253,7 @@ export const GameConfigSchema = z.object({
   instantBuild: z.boolean(),
   disableNavMesh: z.boolean().optional(),
   disableAlliances: z.boolean().nullable().optional(),
+  disableClanTags: z.boolean().optional(),
   waterNukes: z.boolean().nullable().optional(),
   randomSpawn: z.boolean(),
   maxPlayers: z.number().optional(),

src/server/GameServer.ts

@@ -70,6 +70,10 @@ export class GameServer {
 
   // Note: This can be undefined if accessed before the game starts.
   private gameStartInfo!: GameStartInfo;
+  // Wire-only copy of gameStartInfo sent to clients. Identical to
+  // gameStartInfo unless disableClanTags is set, in which case clan tags
+  // are stripped from players. Archive uses the original gameStartInfo.
+  private wireGameStartInfo!: GameStartInfo;
 
   private log: Logger;
 
@@ -753,6 +757,15 @@ export class GameServer {
       return;
     }
     this.gameStartInfo = result.data satisfies GameStartInfo;
+    this.wireGameStartInfo = this.gameConfig.disableClanTags
+      ? {
+          ...this.gameStartInfo,
+          players: this.gameStartInfo.players.map((p) => ({
+            ...p,
+            clanTag: null,
+          })),
+        }
+      : this.gameStartInfo;
 
     this.endTurnIntervalID = setInterval(
       () => this.endTurn(),
@@ -797,7 +810,7 @@ export class GameServer {
         JSON.stringify({
           type: "start",
           turns: this.turns.slice(lastTurn),
-          gameStartInfo: this.gameStartInfo,
+          gameStartInfo: this.wireGameStartInfo,
           lobbyCreatedAt: this.createdAt,
           myClientID: client.clientID,
         } satisfies ServerStartGameMessage),
@@ -959,11 +972,12 @@ export class GameServer {
 
   public gameInfo(): GameInfo {
     const friendsFor = this.buildFriendsLookup();
+    const hideClanTags = this.gameConfig.disableClanTags ?? false;
     return {
       gameID: this.id,
       clients: this.activeClients.map((c) => ({
         username: c.username,
-        clanTag: c.clanTag ?? null,
+        clanTag: hideClanTags ? null : (c.clanTag ?? null),
         clientID: c.clientID,
         friends: friendsFor(c),
       })),

src/server/MapPlaylist.ts

@@ -246,6 +246,7 @@ export class MapPlaylist {
       bots: isCompact ? 100 : 400,
       spawnImmunityDuration: this.getSpawnImmunityDuration(playerTeams),
       disabledUnits: [],
+      disableClanTags: mode === GameMode.FFA ? true : undefined,
     } satisfies GameConfig;
   }
 
@@ -457,6 +458,7 @@ export class MapPlaylist {
         this.getSpawnImmunityDuration(playerTeams, startingGold),
       disabledUnits,
       waterNukes: isWaterNukes ? true : undefined,
+      disableClanTags: mode === GameMode.FFA ? true : undefined,
     } satisfies GameConfig;
   }