feat: adds docker-based dev environment (#18)

* feat: adds docker-based dev environment

* docs: updates Docker command help

* fix local dev

backend/Dockerfile

@@ -0,0 +1,21 @@
+# Backend Development Dockerfile
+FROM python:3.12-slim
+
+# Install system dependencies
+RUN apt-get update && apt-get install -y \
+    curl \
+    build-essential \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install uv
+RUN curl -LsSf https://astral.sh/uv/install.sh | sh
+ENV PATH="/root/.local/bin:$PATH"
+
+# Set working directory
+WORKDIR /app
+
+# Expose ports (gateway: 8001, langgraph: 2024)
+EXPOSE 8001 2024
+
+# Default command (can be overridden in docker-compose)
+CMD ["sh", "-c", "uv run uvicorn src.gateway.app:app --host 0.0.0.0 --port 8001"]