feat: add Docker support and improve /health endpoint

- Add Dockerfile (node:20-alpine, EXPOSE 3456, ENV for session tokens)
- Add docker-compose.yml with restart: unless-stopped
- Add .dockerignore
- Improve /health: add version, uptime, uptimeHuman, per-pool ready/error status
- Listen on 0.0.0.0 for container compatibility
- Bump version to 1.4.0

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

Dockerfile

@@ -0,0 +1,14 @@
+FROM node:20-alpine
+
+WORKDIR /app
+
+COPY server.mjs ./
+COPY setup.mjs ./
+COPY package.json ./
+
+ENV CLAUDE_SESSION_TOKEN="" \
+    CLAUDE_COOKIES=""
+
+EXPOSE 3456
+
+CMD ["node", "server.mjs"]