Add audit logging / change tracking

[quinnjr]

Description

Automatic audit logging for all database changes.

Features

• Track created_at, updated_at automatically
• Track created_by, updated_by with user context
• Optional full change history table
• Configurable per-model
• Access audit trail via API

Schema

model User {
    id        Int      @id @auto
    email     String
    @@audit(track: [create, update, delete])
}

Usage

// Get audit history
let history = client.user()
    .audit_log(user::id::equals(1))
    .exec().await?;