Backend — Database Schema for Entities and System Roles

[specfor]

We need to design and implement the database schema to support Entities (e.g., Police, Water Board, Electricity Board) and System Users (System Admins vs Entity Admins).

• Create an entities table (id, name, description, created_at, updated_at).
• Update the users table (or create a roles relation) to support system_admin, entity_admin, and entity_user roles.
• Add a foreign key from users to entities (nullable for system admins).
• Create corresponding up and down SQL migration files.