Tests: Reorganize test suite into functional subdirectories

- Categorized scripts into tests/unit/, tests/integration/, tests/e2e/, and tests/tools/.
- Adopted consistent naming prefixes (test_unit_*, test_int_*, test_e2e_*, tool_*).
- Renamed conftest_mock.py to mock_config_helper.py for clarity.
- Updated test_int_boot_diagnosis.py with sys.path setup for root-level execution.

tests/unit/test_unit_email_safe.py

@@ -0,0 +1,67 @@
+import sys
+import os
+import logging
+import unittest
+from unittest.mock import MagicMock, patch
+
+# Add current directory to path
+sys.path.append(os.getcwd())
+
+# Mock html2text before importing app.lib_email
+sys.modules['html2text'] = MagicMock()
+
+# Configure logging
+logging.basicConfig(level=logging.DEBUG)
+
+from app.lib_email import send_email
+from app.config import settings
+
+class TestEmail(unittest.TestCase):
+    def test_send_email_missing_settings(self):
+        print("\nTesting send_email with missing SMTP settings...")
+        # Backup original settings
+        original_smtp = getattr(settings, 'SMTP', {})
+        
+        # Clear settings
+        settings.SMTP = {}
+        
+        result = send_email(
+            from_email="test@example.com",
+            to_email="test@example.com",
+            subject="Test Email",
+            body_html="<p>Test</p>",
+            test=True
+        )
+        
+        # Restore settings
+        settings.SMTP = original_smtp
+        
+        print(f"Result (should be False): {result}")
+        self.assertFalse(result)
+
+    def test_send_email_invalid_port(self):
+        print("\nTesting send_email with invalid port...")
+        original_smtp = getattr(settings, 'SMTP', {})
+        
+        settings.SMTP = {
+            'server': 'smtp.example.com',
+            'port': 'invalid',
+            'username': 'user',
+            'password': 'pass'
+        }
+        
+        result = send_email(
+            from_email="test@example.com",
+            to_email="test@example.com",
+            subject="Test Email",
+            body_html="<p>Test</p>",
+            test=True
+        )
+        
+        settings.SMTP = original_smtp
+        
+        print(f"Result (should be False): {result}")
+        self.assertFalse(result)
+
+if __name__ == "__main__":
+    unittest.main()