chore: add pre-commit hook with ruff and pytest

- Add git pre-commit hook running ruff check, ruff format, pytest
- Fix import ordering in conftest.py
- Add placeholder test for test infrastructure
- Generate flake.lock

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1766807290,
+        "narHash": "sha256-7sgUQMKMDvpeu9cwE7mWJfP9N3wJduunmJ/s8LOd9nk=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "4eec65df50d796a8fd9c146a09b5007916ce376b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

src/animaltrack/cli.py

@@ -15,14 +15,10 @@ def main():
 
     # migrate command
     migrate_parser = subparsers.add_parser("migrate", help="Run database migrations")
-    migrate_parser.add_argument(
-        "--to", type=str, help="Migrate to specific version", default=None
-    )
+    migrate_parser.add_argument("--to", type=str, help="Migrate to specific version", default=None)
 
     # create-migration command
-    create_parser = subparsers.add_parser(
-        "create-migration", help="Create a new migration file"
-    )
+    create_parser = subparsers.add_parser("create-migration", help="Create a new migration file")
     create_parser.add_argument("description", help="Description for the migration")
 
     # seed command

tests/conftest.py

@@ -1,9 +1,10 @@
 # ABOUTME: Pytest configuration and fixtures for AnimalTrack tests.
 # ABOUTME: Provides database fixtures, test clients, and common utilities.
 
-import pytest
-import tempfile
 import os
+import tempfile
+
+import pytest
 
 
 @pytest.fixture

tests/test_placeholder.py

@@ -0,0 +1,7 @@
+# ABOUTME: Placeholder test to ensure test infrastructure works.
+# ABOUTME: Remove once real tests are added.
+
+
+def test_placeholder():
+    """Placeholder test - remove when real tests exist."""
+    assert True