fix(config): harden bootstrap logic and add email E2E test

Harden bootstrap_db_config to prioritize .env settings for core infrastructure (DB/SMTP) and only use DB values if placeholders are detected or values have explicitly changed. Added test_e2e_email_send.py for functional SMTP verification.

tests/integration/test_int_email_live.py

@@ -1,29 +0,0 @@
-import sys
-import os
-import logging
-
-# Add current directory to path
-sys.path.append(os.getcwd())
-
-# Configure logging
-logging.basicConfig(level=logging.DEBUG)
-
-try:
-    from app.lib_email import send_email
-    print("Successfully imported send_email.")
-    
-    print("Running send_email in TEST mode...")
-    result = send_email(
-        from_email="test@example.com",
-        to_email="test@example.com",
-        subject="Test Email",
-        body_html="<p>Test</p>",
-        test=True
-    )
-    
-    print(f"Result: {result}")
-    
-except Exception as e:
-    print(f"Error during email test: {e}")
-    import traceback
-    traceback.print_exc()