Add organization management and admin-specific APIs

- Introduced schemas for organizations, including creation, updates, and responses.
- Created models for `Organization` and `UserOrganization` with role-based access control and relationships.
- Implemented admin APIs for managing users, organizations, and bulk actions.
- Added advanced filtering, sorting, and pagination for user and organization queries.
- Updated `CRUD` logic to support organization-specific operations and member management.
- Enhanced database with necessary indexes and validation for improved performance and data integrity.

backend/app/crud/__init__.py

@@ -0,0 +1,6 @@
+# app/crud/__init__.py
+from .user import user
+from .session import session as session_crud
+from .organization import organization
+
+__all__ = ["user", "session_crud", "organization"]