Add Docker production build and update README

- Multi-stage Dockerfile: builds frontend, packages with Python backend
- admin.py serves frontend/dist as StaticFiles in production
- docker-entrypoint.sh runs proxy + admin-api, exits cleanly if either dies
- .dockerignore excludes .env, venv, tests, node_modules
- Split requirements.txt (prod) / requirements-dev.txt (dev+test)
- aiofiles added for StaticFiles support
- start.sh: port checks before startup, venv auto-activation, trap cleanup
- vite.config.js: clearScreen disabled
- README rewritten to reflect current architecture

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

Dockerfile

@@ -0,0 +1,22 @@
+FROM node:20-alpine AS frontend-builder
+WORKDIR /app
+COPY frontend/package*.json frontend/
+RUN npm ci --prefix frontend
+COPY frontend/ frontend/
+RUN npm run build --prefix frontend
+
+FROM python:3.12-slim
+WORKDIR /app
+
+COPY backend/requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY backend/ backend/
+COPY --from=frontend-builder /app/frontend/dist frontend/dist
+
+COPY docker-entrypoint.sh .
+RUN chmod +x docker-entrypoint.sh
+
+EXPOSE 8000 8001
+
+CMD ["./docker-entrypoint.sh"]