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.

pyproject.toml

@@ -0,0 +1,58 @@
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[project]
+name = "billo-release-agent"
+version = "0.1.0"
+description = "LangGraph-based release automation agent for Billo"
+requires-python = ">=3.12"
+dependencies = [
+    "langgraph>=0.3.30",
+    "langgraph-checkpoint-postgres>=2.0.15",
+    "fastapi>=0.115.0",
+    "uvicorn[standard]>=0.34.0",
+    "httpx>=0.28.0",
+    "anthropic>=0.52.0",
+    "pydantic>=2.11.0",
+    "pydantic-settings>=2.8.0",
+    "psycopg[binary]>=3.2.0",
+    "psycopg-pool>=3.2.0",
+]
+
+[project.optional-dependencies]
+dev = [
+    "pytest>=8.3.0",
+    "pytest-asyncio>=0.25.0",
+    "pytest-cov>=6.1.0",
+    "ruff>=0.11.0",
+    "psycopg[binary]>=3.2.0",
+    "psycopg-pool>=3.2.0",
+]
+
+[tool.hatch.build.targets.wheel]
+packages = ["src/release_agent"]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+asyncio_mode = "auto"
+pythonpath = ["."]
+addopts = "--cov=src/release_agent --cov-report=term-missing --cov-fail-under=80"
+
+[tool.coverage.run]
+source = ["src/release_agent"]
+
+[tool.coverage.report]
+exclude_lines = [
+    "pragma: no cover",
+    "if TYPE_CHECKING:",
+    "raise NotImplementedError",
+]
+
+[tool.ruff]
+line-length = 100
+target-version = "py312"
+
+[tool.ruff.lint]
+select = ["E", "F", "I", "N", "UP", "B", "SIM"]
+ignore = ["E501"]