feat: add test suite, tox, pre-commit, and ruff formatting

- tests/: 107 unit tests across config, cache, docker_auth, storage,
  and FastAPI routes; all passing under pytest-asyncio auto mode
- tox.ini: runs pytest via uvx --with tox-uv tox (py311)
- .pre-commit-config.yaml: ruff lint + ruff-format at v0.15.12
- pyproject.toml: pytest config (asyncio_mode=auto), ruff config
  (line-length=140), tox/pre-commit added to dev extras
- Makefile: test/tox/pre-commit targets via uvx --python 3.11
- Source files reformatted by ruff-format (no logic changes)

pyproject.toml

@@ -42,5 +42,18 @@ dev = [
     "black>=23.9.0",
     "isort>=5.12.0",
     "mypy>=1.6.0",
-    "ruff>=0.1.0",
+    "ruff>=0.4.0",
+    "tox>=4.0.0",
+    "pre-commit>=3.0.0",
 ]
+
+[tool.pytest.ini_options]
+asyncio_mode = "auto"
+testpaths = ["tests"]
+
+[tool.ruff]
+line-length = 140
+
+[tool.ruff.lint]
+select = ["E", "F", "I", "UP"]
+ignore = ["E501"]