docs: add Docker deployment guide

[felixvippp-ai]

Closes #102

Summary

• add a multi-stage Dockerfile that builds with npm ci, compiles TypeScript, prunes dev dependencies, and runs only the production app artifacts
• run the container as the non-root node user with exec-form CMD so Docker forwards SIGTERM to the existing graceful shutdown handler
• add a root .dockerignore for node_modules, dist, .git, CI/dev files, env files, logs, and source tests
• document Docker build, run, /health check, and stop commands in the README

Tests

• npm.cmd run build
• npm.cmd run lint
• $env:NODE_ENV='test'; node --test dist/*.test.js dist/**/*.test.js - 69 tests passed

Docker validation note

Docker is not installed in my current Windows environment, so I could not run the local docker build / container smoke test here. The Dockerfile is scoped to the requested production build pattern and should be buildable in a Docker-capable environment.

[mikewheeleer]

thanks for the effort here @felixvippp-ai! 🙏 issue #102 isn't assigned to you, and we merge from the assigned contributor to keep the campaign fair. please claim an open unassigned issue first, then open your PR. closing this one for now — hope to see it back 🙌