P14b: session chat (table + whispers) + saved campaign recap

- Sidebar gains tabs: Chat / Rolls / (GM) Recap. Chat supports table messages and
  private whispers (GM→player via a recipient picker; player→GM via a toggle).
  Server routes table to all and whispers to the target only (+server tests).
- Rolls + chat are persisted to a per-campaign session recap (Dexie v13 sessionLog
  table + sessionLogRepo); the GM's "Recap" tab shows it (survives reloads/sessions).
- wsSync: chat send/receive, optimistic local echo, persistLog for the GM.
- Realtime e2e: GM table message reaches the player; the player's reply reaches the GM.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/src/index.ts

@@ -102,6 +102,7 @@ export function buildServer() {
           case 'playerRoll': hub.playerRoll(sender, m.characterId, m.label, m.expression, m.total, m.breakdown); break;
           case 'gmRoll': hub.gmRoll(sender, m.gmSecret, m.label, m.expression, m.total, m.breakdown); break;
           case 'privateState': hub.privateState(sender, m.gmSecret, m.targetPlayerId, m.handout); break;
+          case 'chat': hub.chat(sender, m.body, m.to); break;
         }
       });
       socket.on('close', () => { clearInterval(refill); hub.disconnect(sender); });