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/integration/test_int_boot_diagnosis.py

@@ -1,6 +1,9 @@
 import sys
 import os
 
+# Add project root to path
+sys.path.append(os.getcwd())
+
 print("--- Starting Import Diagnosis ---")
 
 try:

tests/integration/test_int_schema_v3.py

@@ -8,7 +8,7 @@ from sqlalchemy import text
 sys.path.append(os.getcwd())
 
 # MUST BE FIRST: Mock app.config
-import tests.conftest_mock
+import tests.mock_config_helper
 
 # Connection details from .env (Bypassing app.config)
 DB_USER = "aether_dev"