feat: initial commit — Billo Release Agent (LangGraph)

LangGraph-based release automation agent with:
- PR discovery (webhook + polling)
- AI code review via Claude Code CLI (subscription-based)
- Auto-create Jira tickets for PRs without ticket ID
- Jira ticket lifecycle management (code review -> staging -> done)
- CI/CD pipeline trigger, polling, and approval gates
- Slack interactive messages with approval buttons
- Per-repo semantic versioning
- PostgreSQL persistence (threads, staging, releases)
- FastAPI API (webhooks, approvals, status, manual triggers)
- Docker Compose deployment

1069 tests, 95%+ coverage.

Dockerfile

@@ -0,0 +1,32 @@
+FROM python:3.12-slim
+
+WORKDIR /app
+
+# Install system dependencies required for psycopg binary
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    libpq5 \
+    && rm -rf /var/lib/apt/lists/*
+
+# Copy dependency files first for layer caching
+COPY pyproject.toml uv.lock ./
+
+# Install uv for fast dependency management
+RUN pip install --no-cache-dir uv
+
+# Install runtime dependencies (no dev extras)
+RUN uv pip install --system --no-cache-dir -e .
+
+# Copy application source
+COPY src/ ./src/
+
+# Create data directory for staging store
+RUN mkdir -p data/staging
+
+# Non-root user for security
+RUN adduser --disabled-password --gecos "" appuser && \
+    chown -R appuser:appuser /app
+USER appuser
+
+EXPOSE 8000
+
+CMD ["uvicorn", "release_agent.main:app", "--host", "0.0.0.0", "--port", "8000"]