feat(server): per-viewer capture tally on joined and update messages

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/shared/src/protocol.ts

@@ -1,5 +1,5 @@
 import type {
-  BoardView, Color, GameId, GameStatus, Mode, PlayerToken,
+  BoardView, CaptureTally, Color, GameId, GameStatus, Mode, PlayerToken,
   PromotionType, Square, EndReason,
 } from './types.js';
 import type { Announcement } from './moderator.js';
@@ -34,6 +34,7 @@ export type ServerMessage =
       mode: Mode;
       highlightingEnabled: boolean;
       opponentConnected: boolean;
+      captures: CaptureTally;
       aiOpponent?: { color: Color; brain: 'casual' | 'recon' };
     }
   | {
@@ -45,6 +46,7 @@ export type ServerMessage =
       drawOffer?: { from: Color } | null;
       endReason?: EndReason;
       winner?: Color | null;
+      captures: CaptureTally;
       aiOpponent?: { color: Color; brain: 'casual' | 'recon' };
     }
   | { type: 'peer-status'; color: Color; connected: boolean; graceUntil?: number }