fix: resolve CI test failures

- Added ruff and mypy installation to CI workflow
- Removed deprecated license classifier from pyproject.toml
- Added pytest conftest.py for proper test discovery
- Fixed test paths in CI to match actual test file locations
- All 46 tests pass locally

tests/conftest.py

@@ -0,0 +1,151 @@
+import json
+import os
+import tempfile
+from pathlib import Path
+
+import pytest
+
+from depviz.core.models import Dependency, PackageStatus
+
+
+@pytest.fixture
+def temp_project_dir():
+    """Create a temporary project directory."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        yield Path(tmpdir)
+
+
+@pytest.fixture
+def sample_package_json(temp_project_dir):
+    """Create a sample package.json file."""
+    package_json = {
+        "name": "test-project",
+        "version": "1.0.0",
+        "dependencies": {
+            "lodash": "^4.17.21",
+            "express": "^4.18.2"
+        },
+        "devDependencies": {
+            "jest": "^29.0.0",
+            "typescript": "^5.0.0"
+        }
+    }
+    path = temp_project_dir / "package.json"
+    path.write_text(json.dumps(package_json, indent=2))
+    return path
+
+
+@pytest.fixture
+def sample_package_lock_json(temp_project_dir):
+    """Create a sample package-lock.json file."""
+    package_lock = {
+        "name": "test-project",
+        "version": "1.0.0",
+        "packages": {
+            "": {
+                "name": "test-project",
+                "version": "1.0.0"
+            },
+            "node_modules/lodash": {
+                "name": "lodash",
+                "version": "4.17.21",
+                "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.21.tgz"
+            },
+            "node_modules/express": {
+                "name": "express",
+                "version": "4.18.2",
+                "resolved": "https://registry.npmjs.org/express/-/express-4.18.2.tgz",
+                "dependencies": {
+                    "body-parser": {
+                        "version": "1.20.2"
+                    }
+                }
+            }
+        }
+    }
+    path = temp_project_dir / "package-lock.json"
+    path.write_text(json.dumps(package_lock, indent=2))
+    return path
+
+
+@pytest.fixture
+def sample_requirements_txt(temp_project_dir):
+    """Create a sample requirements.txt file."""
+    content = """requests>=2.28.0
+flask>=2.3.0
+redis>=4.5.0
+    """
+    path = temp_project_dir / "requirements.txt"
+    path.write_text(content)
+    return path
+
+
+@pytest.fixture
+def sample_pipfile_lock(temp_project_dir):
+    """Create a sample Pipfile.lock file."""
+    pipfile_lock = {
+        "default": {
+            "requests": {
+                "version": "==2.28.0"
+            },
+            "flask": {
+                "version": "==2.3.0"
+            }
+        },
+        "develop": {
+            "pytest": {
+                "version": "==7.4.0"
+            }
+        }
+    }
+    path = temp_project_dir / "Pipfile.lock"
+    path.write_text(json.dumps(pipfile_lock, indent=2))
+    return path
+
+
+@pytest.fixture
+def sample_pyproject_toml(temp_project_dir):
+    """Create a sample pyproject.toml file."""
+    content = """[project]
+name = \"test-project\"
+version = \"1.0.0\"
+dependencies = [
+    \"requests>=2.28.0\",
+    \"flask>=2.3.0\",
+]
+
+[project.optional-dependencies]
+dev = [
+    \"pytest>=7.4.0\",
+    \"black>=23.0.0\",
+]
+    """
+    path = temp_project_dir / "pyproject.toml"
+    path.write_text(content)
+    return path
+
+
+@pytest.fixture
+def sample_dependencies():
+    """Create sample Dependency objects."""
+    return [
+        Dependency(
+            name="lodash",
+            version="4.17.21",
+            status=PackageStatus.CURRENT,
+            is_dev=False
+        ),
+        Dependency(
+            name="express",
+            version="4.18.2",
+            status=PackageStatus.OUTDATED,
+            latest_version="4.19.0",
+            is_dev=False
+        ),
+        Dependency(
+            name="jest",
+            version="29.0.0",
+            status=PackageStatus.VULNERABLE,
+            is_dev=True
+        ),
+    ]