fix: Resolve import issues and test compatibility

- Fix Storage class reference in authentication tests
- Add secret_key parameter to AgentAuthentication initialization
- Fix timedelta import in sessions.py
- Basic authentication functionality verified

tests/unit/test_authentication.py

@@ -18,7 +18,7 @@ from unittest.mock import Mock, patch, MagicMock
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), '../../src'))
 
 from auth import AgentAuthentication
-from storage import Database
+from storage import Storage
 
 
 class TestAgentAuthentication(unittest.TestCase):
@@ -28,10 +28,11 @@ class TestAgentAuthentication(unittest.TestCase):
         """Set up test fixtures."""
         self.temp_dir = tempfile.mkdtemp()
         self.db_path = os.path.join(self.temp_dir, 'test_guardian.db')
-        self.auth = AgentAuthentication()
+        self.test_secret = 'test_secret_key_123'
+        self.auth = AgentAuthentication(self.test_secret)
         
         # Create test database
-        self.db = Database(self.db_path)
+        self.db = Storage(self.db_path)
         self.db.create_tables()
         
     def tearDown(self):
@@ -245,7 +246,7 @@ class TestDatabase(unittest.TestCase):
         """Set up test fixtures."""
         self.temp_dir = tempfile.mkdtemp()
         self.db_path = os.path.join(self.temp_dir, 'test_guardian.db')
-        self.db = Database(self.db_path)
+        self.db = Storage(self.db_path)
         self.db.create_tables()
         
     def tearDown(self):