chore(format): add pre-commit and formatter configs

tests/config/test_formatters_present.py

@@ -0,0 +1,14 @@
+import pathlib
+
+
+def test_precommit_exists():
+    path = pathlib.Path(".pre-commit-config.yaml")
+    assert path.exists(), ".pre-commit-config.yaml must exist"
+
+    content = path.read_text(encoding="utf8")
+    assert "repos:" in content, "pre-commit config must contain 'repos:'"
+
+    # ensure at least one formatter/linter is referenced
+    assert any(x in content for x in ("black", "ruff", "isort")), (
+        "pre-commit config must reference at least one of: black, ruff, isort"
+    )