Add production deployment config, Alembic migration, switch to Haiku

- Production Docker Compose with Caddy reverse proxy, Gunicorn, Nginx
- Multi-stage frontend build for production
- Deploy script and automated database backup script
- Initial Alembic migration with all tables
- Switch recommendation model from Sonnet to Haiku for cost efficiency

backend/Dockerfile.prod

@@ -0,0 +1,16 @@
+FROM python:3.12-slim
+
+WORKDIR /app
+
+RUN apt-get update && apt-get install -y --no-install-recommends gcc libpq-dev && rm -rf /var/lib/apt/lists/*
+
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt gunicorn
+
+COPY . .
+
+RUN alembic upgrade head 2>/dev/null || true
+
+EXPOSE 8000
+
+CMD ["sh", "-c", "alembic upgrade head && gunicorn app.main:app -w 4 -k uvicorn.workers.UvicornWorker -b 0.0.0.0:8000"]