Fix code issues and add missing documentation

- Fix duplicate tenant_id parameter in seed.py (line 148)
- Add security warning to SECRET_KEY in .env.example
- Create comprehensive README.md with setup instructions
- Add Alembic configuration files (alembic.ini, env.py, script.py.mako)
- Create initial database migration for all tables
- Document project structure, features, and deployment checklist

backend/seed.py

@@ -145,7 +145,6 @@ async def seed():
                 hashed_password=hash_password("TrustOS-Admin-2024!"),
                 full_name="TrustOS Admin",
                 role=UserRole.trustos_admin,
-                tenant_id="acme-corp-demo-001",
             ),
         ]
         for u in users: