feat(examples): add PostgreSQL example with user relationship

Adds an example demonstrating user, comment, and follower relationship
including:
- User management with profiles
- Comments (not really useful, just for showcasing)
- Follower/follozing relationships
- Ineractive CLI interface with CRUD operations
- Database migrations for the example schema

migrations/20250605215127_users-comments-and-followers.down.sql

@@ -0,0 +1,4 @@
+DROP TABLE IF EXISTS Followers;
+DROP TABLE IF EXISTS Comments;
+DROP TABLE IF EXISTS Profiles;
+DROP TABLE IF EXISTS Users;