WP-0001-T001: service scaffold (Python, FastAPI, uv, ruff, mypy, pytest)

Lands the smallest credible foundation per ADR-0005:

- pyproject.toml: hatchling build, runtime deps (FastAPI, uvicorn, SQLAlchemy 2.0,
  asyncpg, aiosqlite, alembic, blake3, cbor2, typer, structlog, pydantic,
  pydantic-settings); dev deps (pytest, pytest-asyncio, httpx, hypothesis, ruff,
  mypy); ruff + mypy --strict + pytest configured.
- uv.lock committed.
- Makefile thin shims: install / dev / test / lint / format / type / migrate / clean.
- src/artifactstore/ package skeleton with placeholder __init__.py per concern:
  identity, manifest, events, retention, audit, storage, dataplane, registry,
  api/http (minimal FastAPI app, GET / scaffold banner), cli (typer app with
  version subcommand), config (pydantic-settings).
- tests/{unit,integration}/conftest.py present; unit smoke tests assert package
  imports, HTTP root route, CLI version round-trip, settings defaults.
- .env.example documents ARTIFACTSTORE_DATABASE_URL,
  ARTIFACTSTORE_STORAGE_LOCAL_ROOT, ARTIFACTSTORE_LOG_LEVEL.
- README updated with install / dev / test instructions.
- .gitignore: claude local state, local runtime data (var/, sqlite db).

make lint && make type && make test pass on a clean checkout (4 tests, 20
source files type-clean under mypy --strict).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/conftest.py

@@ -0,0 +1,5 @@
+"""Top-level pytest configuration.
+
+Shared fixtures land in this module as the test suite grows. The scaffold
+keeps it empty so unit and integration suites configure themselves.
+"""

tests/integration/conftest.py

@@ -0,0 +1,5 @@
+"""Integration-test pytest configuration.
+
+Integration suites require a database and storage backend; configuration
+fixtures land here as those layers come online in later tasks.
+"""

tests/unit/conftest.py

@@ -0,0 +1 @@
+"""Unit-test pytest configuration."""

tests/unit/test_smoke.py

@@ -0,0 +1,35 @@
+"""Smoke tests asserting the scaffold imports cleanly."""
+
+from __future__ import annotations
+
+from typer.testing import CliRunner
+
+import artifactstore
+from artifactstore.api.http import app as http_app
+from artifactstore.cli import app as cli_app
+from artifactstore.config import Settings, get_settings
+
+
+def test_package_version_exposed() -> None:
+    assert isinstance(artifactstore.__version__, str)
+    assert artifactstore.__version__
+
+
+def test_http_app_root_route_registered() -> None:
+    routes = {getattr(r, "path", None) for r in http_app.routes}
+    assert "/" in routes
+
+
+def test_cli_version_command_round_trips() -> None:
+    runner = CliRunner()
+    result = runner.invoke(cli_app, ["version"])
+    assert result.exit_code == 0, result.output
+    assert artifactstore.__version__ in result.output
+
+
+def test_settings_defaults_loadable() -> None:
+    settings = get_settings()
+    assert isinstance(settings, Settings)
+    assert settings.log_level
+    assert settings.database_url
+    assert settings.storage_local_root