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>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "openclaw-claude-proxy",
-  "version": "1.3.1",
+  "version": "1.4.0",
   "description": "OpenAI-compatible proxy that routes requests through Claude CLI — use your Claude Pro/Max subscription as an OpenClaw model provider",
   "type": "module",
   "bin": {