Add Docker Compose setup for web chat and email worker

Two services sharing a single image:
- web: Chainlit chat interface on port 8000
- email-worker: IMAP polling agent (main.py)

./data is mounted for persistent storage (registrations + conversations).
./openspec is mounted read-only so knowledge-base markdown files can be
edited on the host without rebuilding the image.

Configuration via .env (see .env.example).

https://claude.ai/code/session_015tJePX9eyQENYpJUF8XvvK

Dockerfile

@@ -0,0 +1,20 @@
+FROM python:3.13-slim
+
+# Install uv
+COPY --from=ghcr.io/astral-sh/uv:latest /uv /uvx /usr/local/bin/
+
+WORKDIR /app
+
+# Install Python dependencies — cached independently of application code
+COPY pyproject.toml uv.lock ./
+RUN uv sync --frozen --no-dev --no-install-project
+
+# Copy application source
+COPY src/ ./src/
+COPY chat_app.py main.py chainlit.toml ./
+COPY public/ ./public/
+
+# Make the venv's binaries (chainlit, python, etc.) available directly
+ENV PATH="/app/.venv/bin:$PATH"
+
+# data/ and openspec/ are expected to be mounted at runtime