Phase 18: internet realtime collaboration (GM-authoritative) + server

- Shared Zod wire protocol (src/lib/sync/messages.ts): hosted/joined/snapshot/
  mapImage/error; player-safe projections only (enemy HP masked on the GM before
  broadcast via src/lib/combat/playerProjection.ts).
- wsSync adapter (src/lib/sync/wsSync.ts) behind the existing SyncAdapter seam:
  GM hostSession + debounced snapshot broadcast (useSessionBroadcaster), player
  joinSession into an ephemeral playerSessionStore, exponential-backoff reconnect
  with seamless room resume (GM secret). localSync remains the offline default.
- buildSnapshot (src/lib/sync/snapshot.ts) reuses the same projection as the local
  /play view, guaranteeing parity. Player view refactored into shared PlayerBoards;
  /play?room=CODE = networked read-only mode.
- SessionControl in the header: Host (optional password) → shareable room code/link.
- Server (server/): Fastify + @fastify/websocket + @fastify/static, in-memory
  GM-authoritative rooms (crypto room id/secret hashed, optional join password,
  TTL sweep, players strictly read-only), origin allowlist, per-frame size cap +
  rate limit, Zod validation. esbuild bundle (server/build.mjs), tsconfig.server.json.
- Dockerfile (multi-stage) + deploy/ttrpg.compose.yml (own project on external
  'proxy' net, Traefik labels for ttrpg.briggen.dev, non-root, no-new-privileges).
  CSP connect-src now allows same-origin wss:.

Tests: protocol round-trip, room hub (auth/password/resume/TTL/read-only), enemy
masking, Fastify+ws integration (host→join→snapshot, player push rejected), and a
two-context Playwright realtime spec (separate config) — GM hosts, player device
sees live combat with masked enemy HP.

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

deploy/ttrpg.compose.yml

@@ -0,0 +1,30 @@
+# Self-contained compose project for ttrpg.briggen.dev.
+# Deploy: rsync the repo to /root/briggen-dev/ttrpg/, place this file there as
+# docker-compose.yml, then `docker compose up -d --build`.
+# Joins the EXISTING external `proxy` network — the shared Traefik stack is untouched.
+name: ttrpg
+
+services:
+  ttrpg:
+    build: .
+    container_name: ttrpg
+    restart: unless-stopped
+    environment:
+      - PORT=8787
+      - STATIC_DIR=/app/dist
+      - NODE_ENV=production
+      - ALLOWED_ORIGINS=https://ttrpg.briggen.dev
+    security_opt:
+      - no-new-privileges:true
+    labels:
+      - "traefik.enable=true"
+      - "traefik.http.routers.ttrpg.rule=Host(`ttrpg.briggen.dev`)"
+      - "traefik.http.routers.ttrpg.entrypoints=websecure"
+      - "traefik.http.routers.ttrpg.tls.certresolver=letsencrypt"
+      - "traefik.http.services.ttrpg.loadbalancer.server.port=8787"
+    networks:
+      - proxy
+
+networks:
+  proxy:
+    external: true