feat: Docker, docker-compose, and deployment config (Task 13)

- Dockerfile: two-stage build (builder installs all deps + vite build; runtime copies dist + server)
- docker-compose.yml: 127.0.0.1:3004:8080, named volume for SQLite, env var interpolation
- .env.example: all required environment variables documented
- .dockerignore: exclude node_modules, dist, data, .env from build context
- vite.config.ts: outDir → ../client/dist, /api proxy to :3001 for dev
- .gitignore: remove Docker entries (files should be tracked for deployment)

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

.gitignore

@@ -187,10 +187,6 @@ data/*
 build/
 dist/
 
-# Docker
-.dockerignore
-Dockerfile*
-docker-compose*.yml
 
 # IDE
 .vscode/