feat: production deployment — Dockerfile, docker-compose, SPA serving, classic bot fights

- Add Dockerfile (multi-stage: build frontend + server, serve from single container)
- Add docker-compose.yml for Portainer stack deployment
- Server serves frontend SPA in production (static assets + SPA fallback)
- Auto-run migrations and seed mock bots on server startup
- DB path configurable via DB_PATH env var
- Add "Fight a Classic Bot" button for instant mock bot matches
- FIGHT button queues for real AI opponents

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -0,0 +1,15 @@
+services:
+  botfights:
+    build: .
+    container_name: botfights
+    restart: unless-stopped
+    ports:
+      - "9100:9100"
+    volumes:
+      - botfights-data:/app/server/data
+    environment:
+      - NODE_ENV=production
+      - PORT=9100
+
+volumes:
+  botfights-data: