feat(bot): vsAi/aiOpponent protocol fields and bot-driver registry

packages/shared/src/protocol.ts

@@ -34,6 +34,7 @@ export type ServerMessage =
       mode: Mode;
       highlightingEnabled: boolean;
       opponentConnected: boolean;
+      aiOpponent?: { color: Color; brain: 'casual' | 'recon' };
     }
   | {
       type: 'update';
@@ -44,6 +45,7 @@ export type ServerMessage =
       drawOffer?: { from: Color } | null;
       endReason?: EndReason;
       winner?: Color | null;
+      aiOpponent?: { color: Color; brain: 'casual' | 'recon' };
     }
   | { type: 'peer-status'; color: Color; connected: boolean; graceUntil?: number }
   | { type: 'error'; code: ErrorCode; message: string }
@@ -53,10 +55,11 @@ export interface CreateGameRequest {
   mode: Mode;
   side: Color | 'random';
   highlightingEnabled: boolean;
+  vsAi?: { brain: 'casual' | 'recon' };
 }
 
 export interface CreateGameResponse {
   gameId: GameId;
   creatorToken: PlayerToken;
-  joinUrl: string;
+  joinUrl: string | null;
 }