## Why

The app currently has no deployment configuration — it can only be run via `npm run dev` or `npm run preview`. Adding Docker Compose enables reproducible, single-command deployment to any host with Docker installed.

## What Changes

- Add a multi-stage Dockerfile that builds the Vite app and serves the static output with nginx
- Add a docker-compose.yml for single-command deployment (`docker compose up`)
- Add an nginx configuration for serving the SPA (with client-side routing fallback)
- Add a .dockerignore to keep the image lean

## Capabilities

### New Capabilities
- `docker-deployment`: Dockerfile, docker-compose.yml, nginx config, and .dockerignore for building and serving the static app

### Modified Capabilities
<!-- No existing specs to modify -->

## Impact

- **New files**: `Dockerfile`, `docker-compose.yml`, `nginx.conf`, `.dockerignore` at project root
- **Dependencies**: Requires Docker and Docker Compose on the deployment host
- **Existing workflow**: No changes to dev workflow (`npm run dev` still works as-is)
- **Build**: Vite build runs inside Docker — no host-side Node.js required for deployment