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.

docker-compose.yml

@@ -0,0 +1,48 @@
+services:
+  agent:
+    build: .
+    ports:
+      - "8000:8000"
+    environment:
+      AZDO_ORGANIZATION: ${AZDO_ORGANIZATION}
+      AZDO_PROJECT: ${AZDO_PROJECT}
+      AZDO_PAT: ${AZDO_PAT}
+      ANTHROPIC_API_KEY: ${ANTHROPIC_API_KEY:-unused}
+      POSTGRES_DSN: postgresql://agent:${POSTGRES_PASSWORD:?POSTGRES_PASSWORD must be set}@db:5432/agent
+      JIRA_EMAIL: ${JIRA_EMAIL}
+      JIRA_API_TOKEN: ${JIRA_API_TOKEN}
+      SLACK_WEBHOOK_URL: ${SLACK_WEBHOOK_URL}
+      WEBHOOK_SECRET: ${WEBHOOK_SECRET:?WEBHOOK_SECRET must be set}
+      JIRA_BASE_URL: ${JIRA_BASE_URL:-https://billolife.atlassian.net}
+      CLAUDE_REVIEW_MODEL: ${CLAUDE_REVIEW_MODEL:-claude-sonnet-4-20250514}
+      REPOS_BASE_DIR: ${REPOS_BASE_DIR:-}
+      OPERATOR_TOKEN: ${OPERATOR_TOKEN:-}
+      PORT: 8000
+    depends_on:
+      db:
+        condition: service_healthy
+    restart: unless-stopped
+    healthcheck:
+      test: ["CMD-SHELL", "curl -sf http://localhost:8000/status || exit 1"]
+      interval: 10s
+      timeout: 5s
+      retries: 3
+      start_period: 15s
+
+  db:
+    image: postgres:16-alpine
+    environment:
+      POSTGRES_USER: agent
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:?POSTGRES_PASSWORD must be set}
+      POSTGRES_DB: agent
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U agent -d agent"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
+    restart: unless-stopped
+
+volumes:
+  postgres_data: